Transcript for:
Physics: Work, Energy, Power & Collisions

I don't have to be afraid of physics because it is with you Hi Master Ravi Vanra. so hello everybody This is Ravi Vanra, I welcome you all These are the great platforms of Next Topper Pay. son class 11 chapter number six work Energy Power. very tiny little teeny This is a lovely chapter which is very easy. It is easy to understand and easy to learn as well And its numericals are also easy to do. Bus Some basic mathematics, basic NLM And you should know basic chemistry. if not Even when it comes we are together little by little I will continue learning as I go. anyone who is afraid It doesn't matter. All doubts will vanish with this It is going to happen, son. So let’s get started Of work energy power. So first, a ritual It happens that brother, in this chapter there is energy and If we are talking about power then it is within you How is the energy? then in the comment section Let there be a challenge. How is the josh? its answer Write in the comment box and now we will discuss the chapter Let's get started. But first, understand that What are you going to read in this chapter? What kind of flow is it going to be? So the chapter's The flow is going to be such that some work It will be a matter of work being done. then in energy Talking about kinetic energy and potential energy It will be. The relationship between these two is Work Energy Theorem and Conservation of We will study mechanical energy. Power at Last And there will be an end topic. The last one which The hot topic is called Collisions Of this chapter. OK sir. so let's start Are. Have you ever done any work, any painting? I have done it like Majnu Bhai used to do. Have you ever done this farming work? What Have you done this work? So this is kind of The work was done, right? No sir, I am just studying We do. You are lying about that too, son. When did you do it? When was the last time you used it with your own hands did you write it? remember this. yes, remember, remember, remember Tax. Yes, okay. so we just study I will do it sir. so in today's session or In physics we talk about physical work done We do. We talk about physical work done Are. You are sitting in one place and writing, Are you writing or reading a video from YouTube? you are going, you are watching, you are watching yes, you are being watched. so according to physics You have not done any work since then. even though You have watched a 10 hour session. No There has been no movement on your part. So Physics forbids that you do any It has not worked. none of the work was done Is. So there has to be some motion, some displacement It is necessary to have this work done. So First of all, let us understand that the work is done What is the definition? So work done that component form or vector form It is read in. so necessity says That you should read the dot product first. Because Dot product is going to come in work done. Ok? So a simple solution of the dot product I'll give you a slight glimpse of dot product means a b remember dot Is the product actual sir? a vector dotb vector its resultant which will come That scaler will come. scalar means that whose There is only magnitude. his There is no direction. Ok? So Some of this is required to get the work done Will need it. So let me tell you in advance that Its resultant is R and R is itself is a scalar. That's why this dot product is called Sometimes the book also mentions the scalar product. It is written. Now, we can do this in two ways Let's process it. such as the beta component in the form that a vector = axi cap + ayj cap + az k cap is given. Ok? and b Let vector = bxi cap + byj cap + bz k cap It has been kept. Now for this story, click on dot us Have to remove the product. at that time remember put that son multiply i with i There will be multiplication. J's with J There will be multiplication and K with K there will be multiplication and all of this multiplication becomes 1 1 so remember axbx put ax byx + ay by + az byz these dots The way to do the product is if the vector I have given you the story in the form and if If we have given theta then it is even easier a vector b The vector gives some angle between the two so it's a simple matter sir ab cos theta that is the result of this vector this dot product over sir ab cos theta a magnitude b The magnitude of the angle between the two I have given you cos theta, remember this cos theta theta if is greater than 90° then cos theta The value of goes into negative. cos Theta is negative at that time. If If the value of theta is 90° then sir is the answer of that story cos 90 = 0. and if theta If cos is less than 90° then for that story It is positive. so remember ab cos theta Is. the magnitude of a is the magnitude of b, and The angle between the two will be written in cos. Boss is over sir. This is the dot product Story. Now we can use it in work done do. Why do you know? because work is done Definition It is said that the Force* Displacement. But that vector product It happens with. See, it is said here as well that sir work has to be done work is said to be Done. When was this work done? by a force when The force produces a displacement. Displacement is necessary. Displacement. I mean think about it, if this brother Since when has this force been deployed on this block? It is not moving up. so that means that he did not do any work. move on If it is there then the work is done. but if not move doing. The force is still being deployed. But in between these two, I mean this block It is not making any motion. move a little further It is not there. So this means that physics No matter how much push brother takes according to it No matter how hard you try, physics According to this, he has not done any work have done it. Because the work hasn’t been done yet. The work will be done when its motion is visible. yes sir. then displacement is necessary For work done. So this is a small Displacement becomes a small equation It is said that work done is equal to force* Displacement. but we're big kids now He has gone sir. The matter of nine and tenth will not work. So the work is done, it is written in vector form goes. Don’t forget it sir. Work done. Work Done It is written. Force Dot Displacement Vector. Force dot displacement vector. yes sir, 1 minute. 1 minute. You just placed the dot I told you the product was ready. means force dot displacement dot product means work Dun is a scalar quantity. yes, work done That is a scalar quantity. Scalar Physical There is quantity. Sir Force Dimensional The unit of force is Newton and The unit of displacement is meter. So Newton * Meter. It will be a unit like this Work done which is also represented by Jul It is done. Great sir. then the scalar and Newton * Meter. That means joule is its unit Will go. ok sir work done is dot product of This force and displacement vector and the Work done is a scalar physical quantity. It is a small thing, but it is useful. Displacement is necessary here. Let its displacement be some s If it was there I wrote it down. Now look at two ways than we can represent it Are. Like dot product can also be expressed in two ways represented that in component form and in theta form. so the same thing here If I want to write a word then the component It will be written like this in the form. fxi cap force why see first force then fxi cap + fyj cap + fzk cap and here s is the vector i.e. s The vector is written as displacement It is a vector, it is there in books many a times, right? The s vector is written multiple times as the r vector also it is written so don't get confused it is a xik + yjk + zk yes sir we have written it sir x of i of i with fx x then y with the one with y then fy * y is ok with the one with z fzz finish story sir with the z one. Then We will do multiplication. summing up everything I will give. He ruled by eating and drinking. Such Gujarati I speak. Ok? So we get this The work will be done. second story sir theta de If you have kept it then. So its even easier sir. fs cos Theta. fs cos theta. If theta is less than 90° Displacement happened in this direction. And The force is at some angle which is 90° to the angle theta It is less. So theta positive for that story It happens. Because it is less than 90°. then Even if less work is done we will get positive results. Ok? If it is 90° then displacement is taking place. But it is completely perpendicular to the force Is. So theta = 90° cos 90° that would be zero Is. So the work will be done for this story Zero. The displacement of the story has arrived It is happening in direction. Now a lot of The forces might be acting. From that we I have selected an f. which is some 90° from F creating more angle of displacement with. So for that story theta cos theta will become negative. cos theta negative. i.e fs cos theta work done is equal to negative We will receive it. what is the story coming To understand? Ok. So understand the story about theta too. and this work done story should come in It should also be understood. Look at some small If I take examples from them then you will get more ideas It will come as if understanding this story Because this is an apple. He fell down from the branch. h distance he travelled. See I am talking about distance. But if the same this is direction this is direction Distance displacement is one. But Direction comes in displacement. And Sir, our equation is that of work done there But displacement word is spoken. Not A distance. So, someone should ask you, son. What will he ask, your master is asking. So how much work would have been done by gravity? Tell. Sir, initial position on this process What about this, son? This is the initial position. what is the final position sir? this is the final Position. So look carefully, this is displacement but in negative and sir mg It will also be applied in the downward direction. this forest The force applied on the shape means on the The force applied is in the downward direction Is. OK sir. to force into displacement He used to write like this. Hmm sir. or else fs cos Write it down with theta also. There is no problem. fs cos theta. fs cos theta. be careful Look mg and h both are in downward direction In. mg is also in the downward direction and h is also In the downward direction. So between the two What will the angle be sir? between the two The angle of will become zero. The value of cos 0 There is a forest. So mg and this h will be written as mgh in positive. Why did it come positive? Because displacement And both the forces were in the same direction. That's why it came in positive. Don't be confused. Every child gets this confusion that Sir mg was negative. Even the displacement It is negative. Because of this, both After cutting the negative-negative, the positive came. Or Fight the angle. So this is the story of the angle I have told it in Kopche. don't confuse Be my friend. Ok? Another such story Is. Like I set you up with one In the lift. I got you one In the lift. Now the lift initial position was this Of the lift. This lift is coming down, one of them By acceleration. the lift has reached the bottom Some h distance. So bhaiya also took this bullet Traveled the distance. means below There is displacement in the direction h Ok. So for this story work is done by gravity g means work done by gravity How much would it have been? so sir same story force Angle between the two dot displacements cos theta. Look carefully at this whole In process. is mg in downward direction I must have been involved and it must have been constant. Yes Yes. Displacement in the downward direction Is. yes sir. then it will be mgh and both what is the angle between them sir? cos 0 become Will go. The value of cos zero is one. So Sir this is m g and this is h and this is positive one. It will be written. cos theta cos will become zero. The value of cos zero is +1 so mg h ok sir Why did it come positive? The answer to this is for you Should know. and now there is a story The lift is coming up from downstairs. Initial This was the position. This is the final position. So What work did gravity do in this? Look carefully. So work done by gravity The formula is the same. fs cos theta. Sir In this process mg on this golu bhai The acting force is gravity Gravitational force mg downward direction I will be there and Goli Bhaiya's first time Displacement is increasing in life It is going up, look sir displacement Above this, the direction of h and their The direction is opposite. For this story theta will become 180°. and you will know cos The value of 180 80° is -1. So attention See it from here. The force is mg. The value of h The value of displacement is h and it is cos 180° cos 180° -1 So for this story -mg. So you have to identify that force and Direction of displacement is opposite Is. It is in the same direction. at which angle Is? That story has to be fought. It is coming, son. These are simple stories but they will touch your heart It will strengthen the base. Now this is the beginning It has happened. We have done a lot of such work I am going to ask you questions so that you feel Let us know how Work Done is declared. See If work is done then work energy is understood theorem will make sense because both of these It's a relatable thing. So I am your work energy I want to strengthen the theorem topic Am. So before getting work done, it is necessary to read it It happens. So the questions you will get for this It will give you the actual feel. then ask questions Go ahead and move ahead. and one more question for you It means that a body moves a distance 10 meter along a straight line under the action of Force 5 Newton. This is beyond 5 Newton force It is increasing. Ok? How much work was done? Its induction is given sir 25 joule angle Between force and direction. I asked this Son ji. So the things that these shorts give you Whatever is kept, write it down first. so given Sir G Force according to data given data The value of gave us 5 newtons. How much has the displacement been? He also us It has been told in the question that that is equal Two 10 meters. That is equal to 10 meters. What will be the angle between the two Have to take it out. And we also know the value of work done Gave me 25 joules. So what will be theta Have to take it out. Do we know this concept? Are? Yes sir I know this concept. because even now the son was studying because angle This is the story of. so work done is equal to fs cos theta I can write. Work done 25 f the value of 5 the value of s is 10 and cos theta Have to take it out. 5 * 5 5 25 so come here 5/10 will become cos Theta. So what will you get? cos theta is When is the value of 1/2 in cos equal to 1/2 does it come? Sir theta is equal to 60° then It comes. So, our right answer will be That is equal to 60° A for Arjuna. it CBSE PMT 1997 This is the question I asked when I was born It did not happen. Ok? so 60° right answer yes Sir right answer. So the first question was ours A fantastic one. going to another question I am doing it sir. This one is a little feel-good. It's a little feel like watching when a body moves with A constant speed on a circular path. means it is running at a fixed speed In a circular path. shrut shrut such circular If you are starting motion then work is done without tension Force is asked here work done by Tension Force In this story, we are going to take out the work Done by Tension Force What will be the tension force of this work done ok this is what I mean by these tension I took it as an example because here He must be acting, he must be spinning it Which force will it be sir, it will be tension force which is rotating it in a centripetal direction You can take the story also but I I had set an example by drawing this diagram That's why I wrote Tension Force. Ok? So sir tension force and this velocity Look, if I cut out a small section of this So whenever this particle will be here then The displacement would have happened in this direction In. Yes sir. tension for this story what will be the direction sir? This will happen. Yes It is centripetal, right? Ok. Now this Particle suppose arrived somewhere here If it happens then this will be the direction of displacement That will be ds. Ok sir. For this story Whatever force and tension there will be, what kind of thing will it be? This way It will be perpendicular. So you can choose any section Take it out for. suppose that you turn around Here comes this small displacement dx whether I write it or dx it doesn't matter Is. But whatever will be the direction of the tension, The direction of the tension force will always be will be 90°. what will it be? It will always be 90°. So If someone is making a circular motion and there is This tension is due to centripetal force Playing a role of a centripetal force. Sir, did you forget what centripetal force was? Those who rotate it in a circular motion The force is called centripetal force. So This is the tension force here. So tension The angle between the force and this displacement And this angle between displacements is always what are you getting? I am getting 90°. 90° Mill Used to be. So you can directly write that the work done fs cos 90 now because cos 90 The entire work done will be zero. So It will be told that the work done will be zero. Acceleration will be zero. No Force Acts On a body. Look, you should also check if I am there Which options are correct in this? or how can it be corrected Is. So the first thing seems correct to me. Work done will be zero. Are getting. Acceleration will be zero. See, this is the story No, it is a little correct. If the acceleration It would have been correct if you had said magnitude. Why? because speed he told that speed How is it? is constant. So the acceleration If you had said magnitude it would have been correct. But He said acceleration. Acceleration is itself a vector quantity and its The direction will change continuously, right son? That too will be under the direction of the centre. This way in the same direction as the force It will happen in. Then this will be wrong. It was correct to say magnitude but Acceleration is a vector quantity. Therefore it is not correct. no force act on a Body. no sir tension force is acting Is. Only then can it move in a circular motion Used to be. So this is wrong. sarah this is This is a lie. Then It Is The Velocity Remains Constant. Look, this thing about velocity is wrong Is. If we change the magnitude of the velocity Here the velocity and its magnitude If we did, we would have accepted that it is correct Because speed is constant. But He has said velocity. Velocity and The special thing about acceleration is that sir this vector There is quantity. so continuously his The direction is changing. So this thing It will go wrong. CBSE once asked There was a question. Always think that this How else can the option be modified? Was? So better clarity of questions I will get it. Ok sir let's move forward. One More The Questions We Have Comes in vector form. look at a small The particle moves and its position is given that take this position from here from its Initial position here. meaning initial The position has been given. Oh what an amazing thing Is. Look, look carefully. a what what I have given it. Given data. Let's write it down once. You will see, you will understand everything here. But I will try it once with my own hands Should I ask questions along with sir? So look at The initial position has been mentioned and The final position has been told. He has given the initial position rip is equal to see 2 i cap + 3j cap plus I have given it with 4k cap. OK sir. and the final The position is also given here r final How much have you given sir? R Final R Final is equal to 5i cap minus 2j cap and this plus K ok sir so this Get the full displacement vector You will go. Yes sir. So displacement Vector is equal to r final - r initial. So you will get this displacement Vector. like five of the final 2 taken out this will come 3i cap. then these -2 more This is -3 so you will get -5j cap. then this k cap and here it's -4k so this is minus 3k cap r final - r initial has to be done. So There you have it, the s vector. look carefully What have you got? s is the vector whose The magnitude is such that its vector form is I can write 3i cap - 5j cap plus minus By doing 3k cap. Ok. One thing. This is one thing. I did not give it directly. of JEE Mains There is a question. How can I give it straight, son? Some? You will have to do the work yourself also. So this is a Every thing was given separately. So we first have S Took out the vector. Force vector already I have given it. The force vector is already here I have given it. as force vector is equal To 5 i cap + to 2j cap + to 7k cap. Just what do you want to do sir? We have to take out Dot product. we have to remove the dot Product. So, f work done is equal to f Dots vector. f. what is there to do here? We had learnt the method. to the one with i Together it will become 5 * 3. plus this one with j With j it is 2 * -5 OK sir. Plus this 7 into -3. in Multiplication of both 5 * 3 = 15 - 10 and this will become 21 how much will it be Its answer was 10 out of 15. 10 subtracted from 5 will leave 5 in the meantime So the answer will be -16 once Please verify my calculation Your calculation is weak son, it is better than mine If possible you can tell me in the comment box Please tell me if I wrote the answer correctly or written wrong in JEE Mains 2023 The question asked was this Extracted the displacement vector. Ok? After finding the displacement vector, what Did? Force into displacement. I Wale Ko with the I one, J one with the J one with, the one with the K with the K with direction with sign used minus then Minus, plus, then plus. see minus plus I did not make a mistake and this answer is correct Is it written or not written? Comment Section I will tell you and then proceed further. Ok? Now a new question is before us. New Look, there is no question. whatever so far You have read the story, right son? So there There was force, it was constant. Here I have I had also brought it in writing that the Constant Force Work done due to constant force. Now force can also be a variable. yes can use that force over time Magnitude increased. That force for 5 seconds It was 5 Newton. Then for the 10th second he Every second one newton is increasing Is. At each displacement i.e. first 5 There was so much force for the meter. then further That display of force for every meter The magnitude of is increasing. This means this It happened that the magnitude of the force was changing Or the direction may also change. But the magnitude of the force is changing It is continuously. any one form any one Any one function according to the formula Regarding. So here I wrote generalized so that f = 5r² + 3 means r = displacement here. So As the displacement changes It will change accordingly. It is written 5t here. Is. As time changes, time means If time changes then with time this The magnitude of the force is also changing. It is also written here ar² plus b / r This means that as the displacement I will do it very well, I can do it either x or y Can do it. So as it is Displacement will vary, however the Verrry will do it. hey so what is the value of f variable Example is that force it is the function of Displacement. displacement or Position. Along with the position it is also very Is. So I have made a graph of this? Force versus displacement. its graph Have drawn. So sir look here the force Was increasing in the first initial. was growing, it was growing, it was growing, it was growing, it was growing Had been. then decrease, decrease, decrease, decrease then It increased a little bit and then started decreasing again. Now this Force versus displacement for the story We have drawn the graph of . But How to find out work done sir? So we had a little I used my mind crookedly. What did you plant? crooked I used my brain. according to that crooked mind We have done a little work, son. Taken out. Small one. such as this formula It happens. We all know this. So, I Found its differentiated formula. d.w. wrote. dw = force dot small displacement. There is force, whatever is felt is the force. Who It seems to be the same force. but a small For displacement. this dr For displacement I am going to write this Am. Now see how dr can be written? This is the confusing part. So let's learn Here. Yes. Let's learn this thing that DR How did you write it? do you know how to write r sir? XI caps+ Know how to write YJ cap + jk cap R. dr how Write? dr sir dr you are my dear sir. Not dr. It's dr. So dr dx i cap + dy j cap. Keep deantiating. small so small Differentiation and this dz k cap. Now this thing Apply it there. So look small work done dw equal to aa jayega fx i cap look carefully Or if you want, you can write it here. See, proper form means ugly form, not ugly form instead of making it i write it so that dr This is how you can change dxi cap dy j cap dz k cap if you are given the factor of x if it is there then you should like x, if it is given with z then this I am taking the product with z and giving the product with y then do dy, do dr instead of r which That respect should have been given in respect You can use it. I am taking this as a bada sa form I don’t want to make it. I just give you this I want to teach you that when force is variable Write a small work done for that time. fdr do it. Then integrate it. Then this Integrate the thing. means dw If I do the integration, I will get it Work done. and dw is written as equal to Force dot displacement. Now it might be possible that instead of dr there can be dx, dy and dz yes. could be possible. there is no doubt about it There are no things. See, I would write it like this I am sure that work is done if x is discussed. If x If it comes to this then this is how fx integration will happen dx would be written like this. Yes sir. if work done If it happens that this is fy then we will write fy dy. I will write dy. Doing vector product on this There is no need for it. Why it is not needed Son? because see dy and dx are the same Will be in direction. so cos of this story What will happen to you? cos cos for this story It will become zero. The value of cos 0 is one will go. cos theta = 0. So cos The value of zero will become one. so fy.dy You can write directly. or the force Write the equation. fxi cap + ayj cap + fy j cap + fzk vector form of cap and dr these Write. Then a big form will be made. We don’t want to make that. 1 minute sir one by one A new thing is also coming to my mind. What I know, this sounds a little familiar. We had noticed one thing sir, that never The format comes. Integration format Comes and the one behind is dr vector. dr dt whatever ever happens. So behind one if it is on the x axis one if it is behind x be on axis and This front one is on the y axis. So one thing It is said that the area Under F vs R Area Under F vs R it's given as a work done these days will give the value of . What an amazing thing you said. This will help you solve small questions and MCQs. Based questions will be made that area under The graph of force versus displacement will give you Will give value to the work done. OK sir. So two very great questions. I will get it done. The first question before you is A force versus displacement graph I have given it to you in the diagram. Ok? work done by the force on Moving the object from x = 0 to x = 6. means to move from here to here which Tell me sir whether the work will be done. Ok? So these In short, this area will be our answer. will be. This area will be our answer will be. So sir this is the area of the first square Take it out. Then find the result of this triangle Take it. It's over. find our answer Went. So sir work done is equal to area Under f is versus displacement. so this If the displacement is in x then f versus f Graphed s versus x. yes sir. So Its summation will be like this. This is the first one which It is becoming rectangular. means this distance How much is it? Three. And what is this height? Three. There are only three. There are three sir. Ok. 1 2 3 so This is 3 * 3 + 1/2 How much is this distance sir? three to six means Three. and what is his height sir? These too are three. OK sir. So 3 9 and this means 9/2 9/2 4.5 4.5 + 9 then the answer is 13.5 13.5 Will go. Look carefully. Is yours too The same answer is coming which is becoming my answer Is? Write in the comment section. before me Write and tell me that yes sir B option is Correct. Option B will be a perfect fit. Asked in CBSE PMT 2005 There is a question. Ok. Now first I see I had told you one thing about the area under graph It was a matter of. Ok. second sir this is vector form The point is that there should be force dot displacement can give all three X Y Z in all three If I have it then I will use all three. but this If X is given for the story then X If I have given it in Y then it is in Y. So such a Amazing question asked in NEET 2019 In. Look these are such questions, I mean sir we So I am preparing for the boards. You Why are you getting NEET questions solved? These NEET questions JEE Mains questions You see conceptual clarity. To you I am scared of Physics. why are you scared Do you know? because every time you ask me questions son Do you read it and then leave or just do work Dun, Scalar Physical Quantity, Dot Product, then force into displacement. Yes sir, frame dependency. So, a few times You just memorize the thing and go ahead. that apply Learn to do it. How will you learn? Will you ask questions? You will ask good questions. good questions Examination means it gives you conceptual Ask questions. So from there your The clarity further increases. Meaning Concept Understand the. Don't hold on to the examination. Understand the concept well and know how to apply it Can be done. you will ask questions like If you get the good ones, you will get the feeling from there that yes what we have read is like this Can be applied. this is it in life Have to do it. If we are studying physics then our This has to be applied in life also, I read in the book that this is real life Is it applicable or not. studied like this She goes. not like a book by rote I mean turn the pages of it. Definition Memorize it and move ahead. No, read it like this. See. So what is the question before us? The reason behind your anxiety That is why you ask questions on majority of the time. You run away from it. Don't run away from questions. You will try to do more questions. These Got four questions asked. I myself am 10 I will ask more questions, son. such mentality Please Keep. I have given a form of force Is. 20 + 10y x on a particular y direction where f is in a Newton and y It is in a meter. I mean look at this question I mean the special thing about the examination is that it Majority of the time whatever information is there He tells us exactly where the force is here It is in Newton. y here means in meters It is in SI units. I told you in advance. Ok? So we have nothing to worry about It is in it. work done by this force work done by this force due to move particle From y = 0 to y = 1 m. things that I have given it to you and I am continuing writing. We I just learned one thing that if I get the work done We have to find out the variable force. is this Is it a variable force? Ask first. Yes sir. These It is depending on y. this is the force of The equation is dependent on y. means this is the variable force. Write it in your book I write that this is an example of variable force Is. So from there you will get to know that yes Sir. These types of questions may come. every I have asked one type of questions in this session I mean I have written it and asked it. So you Clarity will increase. OK sir. Read. Us what do you want to take out sir? Work done. after work done what was the form for that sir? Force Displacement dr vector. Now carefully See. this is in y so I'm just gonna do y I take the product. Meaning that I take fdy. cos will become zero for dy. cos of zero The value will become one. so we have to worry about It is not a matter of that. Write straight. fy equal to How much is it? 20 plus 10y is 10y. and not die by it's a dy by means to be afraid. In Gujarati I say it. The integration of dy will be like this With 20. So 20 * dy plus one of this dy Multiplication with 20 happened second time times will be multiplication with 10 10yd will be written with a plus Look, whatever constant is there, take it out So once you get the integration of dy, you will get The second time 10 will go out and the second one will go will become yd for . Upon integration, you integration of 20dy will give y + 10 as it The integration of y.dy is y²/2 whence What is the limit here sir? From Zero The limit is up to one. from zero to one There is a limit. I have written it sir. Now a little bit Let us simplify it. 20 * 1 - 0 so be it will go to the forest. This will become a forest. need to write There was not any trace of it, Sir. Any chance to write this down There was no need. So I wrote 20 as it is. plus look it will be 10/2 five five then y² y² once the square of 1 By minusing the square of zero, we get 1² - 0² If it goes then what is 1²? the forest is It happens. There was no need to write. 20 + 5 25 joules will become its right answer. you are a Tell us in the comment section if you like it too Is this the answer coming or some other answer coming Is? Please tell me in the comment section The answer you will get or not. 25 B for Bachchu Brother. Ok? So 25 joules will be the correct answer Will go. Let's check yes sir. option b is correct It will go smoothly. Perfect to the point even. Any Is there anything to worry about here? No Sir Joe I have applied whatever I had read. Any new I did not read anything. And it is not that these It is not in the question. in your NCERT Look Even better questions Are. There are very hard questions too. Yes. Now I have a small question for you I throw it away. Is this work done? that frame It depends on the pay. I mean who is the observer Yes, this thing depends on that. are there any He might be looking at it from a sphere of meaning. Any It is possible that the speed in the sphere of Earth A train is moving from here, look through it It may have been so. Maybe someone from Chanda Mama You are taking observations. So for every case Can Work Done vary? Any in a particular situation or In particular incident. Yes sir. that depends In which frame of reference will the observer He is sitting. why so sir? Because which The force depends on the reference frame does not. but displacement depends depends on which reference frame you are viewing from had been. So in short this work is done and that too It will become frame dependent quantity. That Is this asked in MCQ or a marks with two marks small Can be asked in the question. This It is a useful thing to write after doing IMP. These Writing by doing IMP is a workable thing Son. Any problem? It is a very clear cut. Excellent. Move ahead. this is the whole thing Whose was it? It was a matter of work. Work done ki baat Was. It was a matter of work. Work means worker. Work means work done. Ok. now the second chapter That means we are going to start with the energy part. We are going. There is one more question for you that When the body moves at a constant speed at That time what about the work done? this is it The same question came back. I have got the question done. This I hit delete. ok sir hit delete Gave. I got this question asked. Ok. I thought you might have a different question For. Well, we are going to read the new part. Which is energy. You must have learned by looking or You must have thought that I should eat and drink something then I can do some work. without eating or drinking this Motu doesn't use his brain. So samosa It is necessary in that Motu Patlu case. So energy is needed to do some work For. How much ability do you have to work It is defined by this energy. So Energy of a body is defined as a Capacity and an ability to do work. How much it has the power to work within it The idea will give energy. Ok sir. Very This is a nice lovely definition. Now Energy Is of a body is measured by the amount of work Done The Body Can Perform. means defined like this You will know how much work he has done Energy is defined by what we have done I have seen so much from one place, look here It seems like it caused a stir here You know them all over the city, you know them If you know them then write in the comment section Its name is correct and also which movie it is from If you write this, see, it created an uproar for them The energy inside it was very high, so it Energy created a stir in the whole city I have used it for work, now my energy is gone So he tried to steal the energy. They tried to steal energy. Any from a vehicle in electrical form absorbed energy and now back to wrath He will create havoc. So energy is a kind of work It is used. So how much work did we get done Will give idea about energy. like this powerful You used to see Panchatva in that serial, right? How much energy is there in this form? These different form of energy, this is a different form of energy form, this is a different form of energy, this is energy A different form of . Then he gives some of this to the country Make something to save the world If a person works then his energy is generated by the work It is defined. So energy is kind of Work is relatable to work done. Work Done It is relatable to. So remember to work and Dimensional formula of energy and its The unit is the same. Work and energy It is relatable. then the unit of both would be same Is. The joule we used to write for work was There will also be a unit of energy. of energy The unit will also be joule. Ok sir? Joule = Newton used to write * meter. MLT Form You know, still there is a comment in the comment section Write the dimensional value of son Joule Formula. And see its different-different There are also forms. Such as arg, Electrovolt. This is in 12th though You will read the calories. then these upcoming chapters I will study. Then it's on kilovolts. These All units are there. Whose? This is the unit of energy. So Energy One Extract 10 to the power is equal to -7 joules. 1 Electro volt is equal to so many joules it occurs. one calorie equals to 4.2 something It is approximately 2 joules. these kilowatts But it is also a matter of hour. I will tell you after reading this. I will tell you this myself. Ok? All the other things can be remembered as well Is. Do you know if this actually exists? it What is an erg? is CGS unit. Erg that is CGS unit. These CGS There is a unit. one erg one erg e r g one erg is equal to hota hai one Just like if there is Newton then it is here Dine. ye dine ok sir dine and into Centimeter. Centimetre instead of metre It is called Arg. this is equal to 10 to Power -7. You can prove it if you want yes. I mean give it to you for now. They are useful. One is this and the other is what I am doing right now I will tell you. Don't be confused about this. This is me for a little while now I will tell you later. Leave some time on the kilowatt This above story will be for some time. Ok sir. So energy, like work, is scalar There was form. Energy is also a scalar form. The unit of both is same. of both The dimensional formula is the same. Different-different units can also be written Are. You will study this in 12th. he is just in 11th The second part is the second book. in that Will you read it? But once I give you the induction Gave. If you see it somewhere, don't get confused. Things already written in your book will remain. OK sir. Now look different-different Form can contain energy. Like that punch The element I talked about. So it might be The energy must be in the form of heat energy. yes It may be in the form of solar energy. yes It is possible that this can be used in the form of wind energy. Energy may be hidden. It could be that this hidden in the form of mechanical energy, which I am going to study it now. It may be so, Sir, It is hidden in the form of nuclear energy There is energy. It could be that chemical Energy. So, there are different types of There will be elements. the one that is different Out of the different types of energy Some will accept and act upon. Ok, Sir. Now we will go to study mechanical energy. Remember this is electrical energy, sound energy, magnetic energy, Electrostatic energy. Although, I have also explained electric energy. So These are all forms of energy. So Energy can be in different types it occurs. This will be studied in 12th. This too In 12th. This is the last chapter of 11th. Then we will study mechanical energy here. This is this energy. we are going to read it now Are. Mechanical energy is nothing is new. Mechanical Energy Sir. kinetic energy pas plus potential energy is converted into mechanical energy It is called energy. Kinetic energy is some is caused by motion and this potential energy due to some situation, some position It happens because of. just some confusion It happens because of. In detail, we both We will go to study what kinetic is Energy? What is potential energy? So the first part is kinetic energy what happens? So sir any one month is there. That Mass has some velocity. so sir 1/2 mass * velocity ie 1/2 mv² that is the Form of kinetic energy. that is the form Of kinetic energy is gone sir. Kinetic Energy k = 1/2mv² Here v means velocity. OK sir. Now See, this is a scalar physical quantity. This Isn't it so? It is also written like this. see 1/2 1/2 m v vector. Vector v Vector v Vector Mean what will happen sir? v.v v² and the dot product Is. This means that these scalar physical There is quantity. yes sir i understand this one thing I. Now the second thing to look at is this story I told you I told you. Let me tell you another story. 1/2 mv² How did you come? How come 1/2 mv² = p² / 2m? Can I write like this? 1/2 mv² Into into one mass multiplied by the mass divided ok sir good should i write I can use this term above 1/2m here. It will become Sir Mass in mass multiplication m² v² / 2m mv what is momentum then p² will be divided by 2 so p² / 2m it is also one form of a kinetic Energy p² / 2m Smaller MCQs Can be made ready. I comment here I will write it in the section. MCQs come Can be done. Wrote it in Kopche. OK sir Kinetic energy is a form of energy. Dimensional formula of energy m1 l2 - 2 Its unit is joule. SI unit joule It happens. Ok? is not the case. The latest This is the thing. This is it. it's a frame Dependable. This is the newest thing. Why? What is frame dependable sir? Its This means that it depends on the frame Is. Yes sir. this gun bullet has no speed is going from. Suppose that you have it You have super sonic power and you too are Golu Instead of becoming a brother, you became that Super Sonic. You You are going at the same speed as The gun is going off. according to you what you say? Sir you are Sonic Super You with Sonic. You will say that the gun The bullet isn't even firing. Why? gun According to me the relative speed of the bullet This is zero according to the super sonic guy Is. So if it's written as kinetic energy The speed of the bullet of the gun is 1/2m v Square of Relative. so it is equal to It will become zero. means kinetic energy is Zero for the Super Sonic guy. But for us it was 1/2 mv². this is it This is a strange thing. So sir it is velocity right? Velocity it's a relative term. Velocity The frame depends on which frame Some guy is sitting and watching. so this Super Sonic. I'll write it super sonically Here. Super sononic. remember this is super Sonic. So we are also running at the same speed. So The relative velocity became zero. Relative velocity zero 1/2 m v relative to Square. In respect of this we are looking at Are. So this brother will say the same thing. So Kinetic energy became zero. these frames It is a dependable quantity. Remember this. Ok, Sir. Another example of this. Another brilliant one Question. has there ever been a discussion about kinetic energy can it be negative? It asks you a question I have been. has there ever been a discussion about kinetic energy can it be negative? Yes. Kinetic Energy with Any Frame References. any frame of reference According to this, should the kinetic energy be negative? Can it? Think, just think. Think, just think. Yes, it is possible sir. it could be this gun Bullet of a gun at 5 or 100 meters You are running away from seconds. And This guy with Super Sonic was super Sonic. S S Sir this Super Sonic guy If he was running at 200 meters per second then The relative velocity here will be According to the person it will be minus I am 100 yes sir that is correct so should I I can say that this super kinetic energy According to the Sonic guy, this guy This guy will say whatever he tells Sir tell me how kinetic energy will be written 1/2 mass of that gunshot okay sir and 100 in minus and its square head The square is coming because of this Even if he is in negative he can become positive This means that the kinetic energy Can never be negative. always Positive. Always positive. Mass not negative It is possible. Velocity can be negative. The form of kinetic energy was like this 1/ square of 2m v. then the velocity is negative It can. But it's getting square. The square due to which it comes back to positive It is being made. Ok? So always positive. Ok? Will you remember this incident? will remember this talk? Small question but useful Question. So always remember this one thing That always positive. Kinetic Energy Is Always Positive. Look, these were small points. I wrote down the work for kinetic energy They were from. And one more thing, this is kinetic energy Don't look. Can this kill someone? Gunshot. Yes. So it did a task You did it. even if someone is killed Did some work. Look, it's piercing the bone from here it entered inside the body and then It might even go out. It is possible It should remain inside. So he did some work Did. This bullet also did some work Did. Even if he killed me, he still did some work Did. So this kinetic energy is used for some work It is used in. so the amount of work Done. the amount of work that the moving object does what can do before coming to rest is equal to Kinetic energy. I mean a gunshot That which was in motion, is about to come to rest will do some work. which shoots a gun It came with speed. that speed slowly slowly It is decreasing when it enters the body And at some moment it came to rest. So It must have done some work only then it got completed All the kinetic energy went away from it. has come to rest meaning the kinetic energy now Has gone. So where would the kinetic energy have gone? She must have converted into that same work done. Which work was done? yes kill the guy Give. Ok? that neither with weapons nor bullets From. The guy is not afraid. I forgot it. Do you know that entire poem? Don't know? hey friend what about prince ji It was a very lovely poem. Yes Oh no, do you remember? Comment Section Friend, write to me, you will remember this poem Yours. This poem must be remembered. If it isn't there then you will remember it now, son. What that not by the edge of a sword or by bullets From the shower. The only thing a person is afraid of is From God. Whose poem was it? Do you remember this? No not by the edge of a sword or by a shower of bullets If a person fears only God then whose fear is it? It was a poem, son, maybe you wrote it in the comment section It is possible that you are a Janji person so this You might not have seen the movie, well we Whose story have we read in its entirety? Now we will work on the kinetic energy for Son, you are going to study energy theorem. Take this and print it properly then use work energy Let's start the theorem. So come on son Let us understand what the work energy theorem says Is? Work Energy Theorem. See. Now work The energy theorem gives the statements such that Sir work done by all the forces is equal to Change in kinetic energy. It means that which Change came in kinetic energy that work was done It might have been converted into. or the work we did what has happened is the change in kinetic of this system Has become involved in energy. Such as You just saw a diagram. One of its when we strike the iron with a hammer let's shout dhak dhak dhak dhak so here What happened is that its kinetic energy changed Some work has been done here, this is its stone What did you have nearby? When I threw the glass it broke, sir This stone had kinetic energy which Glass breaking due to kinetic energy The work is done, what happened here that Just like water will come after making such a tour When it came, that water had kinetic energy Because of which it is moving round and round The work is done, the incident is same here too The wind had kinetic energy. That This work is done when kinetic energy is converted I am getting into form. some work is getting done Is. So this is what I wrote that Sir Kinetic Get involved in getting energy change work done Used to be. or the work that is being done for this change in kinetic energy It is responsible. Sir, from which forces? Because work done? whether it is gravitational force, Whether it is tension force or normal force no matter how much the friction force is internal force or any external force yes, the net force, net work of all the forces done, net work done it is equal to change in Kinetic energy. change in kinetic energy what happens? I liked some system. Correct Is? Let the initial velocity of the system be Let u be 1. The initialization of this system The velocity is u1. Ok? so 1/2 1/2 mu² and 1/2 v² are the final kinetic energies It will be done. Yes sir. So this change is kinetic Energy is equal to net work done. So it was written The statement 'The work done by net force' will be displayed. work done by net force or all the forces is On a body is equal to change produced In a change in kinetic energy. Meaning Change This will be equal to this kinetic energy. Are you able to understand this? two of it This is a derivation. A Constant of Forces Proof for Work Done Due to Cause Please tell me sir whether this statement is correct. This which What is written is correct. Panacea is work Energy theorem should be written in small letters like this Meaning WT will also be written in small form. If you see WT sometimes, then this represents the work energy theorem Is. And this is not limited to 11. These It is a panacea son, it will be useful in 12th also. It will be used a lot. Well, let's talk that its two derivations are given in our syllabus They are kept and are asked about a lot In a rapid manner. So a constant Because of the forces we were proven And because of a variable force we get the proof Prove that this statement is true. These The form and equation written is correct. First it's the turn of constant force. So look at a The mass is the initial velocity u. Initial kinetic energy will become 1/2mu² and Its final kinetic energy is 1/2 mv². So There is an acceleration which Because of this there is a change in its velocity and that's the acceleration constant because The force is constant. We are walking in the belief that the force is constant here due to which The acceleration is becoming net constant. And because of this we have to prove it, son that work done by all the forces is equal To change into kinetic energy. great sir talk. Ok. If you look at it in actuality then this is it What? Work done. this is one i can do Am. Look carefully. I do this in one place can i see how i wrote acceleration Will you go? So here the equation of motion is used we can do it because this acceleration is constant. So the equation of motion is like If you will use it then according to the third equation According to the third equation of motion, what is can I write like this? v² - u² = 2as yes sir v Cain Wright. Now look carefully, am I I can do that with an acceleration of If I take the value out from here then v² - u²/2s Yes sir. you know the work is done Equal to is force * displacement. Yes sir, I know this. Look Force What is the value of? Mass * Acceleration You can write into displacement. Mass Age It will remain like this. Write the value of acceleration. v² - u² / 2a 2s and by adding it into it we get s. Did you understand this much? what did we Did? The formula for this acceleration is here We have pasted it. OK sir. be careful Look brothers and sisters. Do you get to know Used to be? hit the ss. We took out two Fired it up. then 1/2m with it once Multiplication will happen. second time its Multiplication will also happen. So 1/2mv² minus 1/2 mu² 1/2mv² means final kinetic energy. 1/2mu² Meaning initial kinetic energy. Yes. So In sure this work is done which net will be available or net By all the forces you will get it. it is equal to Change in kinetic energy. For whom first Did you get the proof, son? this work is done by all the Prowess came for the Forces. what happened To understand? Do you understand this now? Attention See it from here. This is asked about derivation Can be asked in two marks or three marks Can be done. Write to you in nice words should also come and this acceleration drive You should also know how to putt here. Here Just put acceleration and simplify Have to do it. remember yourself once son If you do it, it will happen. Constant force. Now because of variable force. so whenever If variable force comes then it is time to write 'work done' You will understand the method. Force Dot Displacement. yes sir. Now look at the force The value I can write is mass * acceleration As written earlier, same to same sir acceleration is the variable here so when When there is variable acceleration then we let's use format sir acceleration = dv /dt what do you write dv /dt so I Here it is written Mass as it is. Acceleration = I have kept the dv/dt and s as it is ds. Look carefully. I will delete this t and I'll take the other side. means that the mass Mass is constant. Even though you are out You can take it out. OK sir. Mass I Out I took it out and wrote dv ddt on this side Took it. Wrote it in the form of ds / dt. did you understand a story that ds / dt So, there is velocity. so wrote it down velocity dot dv. a nice fun thing It will come to your mind that the work is done by all The forces or network work done is equal to In integration the mass is outside and this is what The formula is vdv What will become after integrating vdv v² / 2 From where to where is the initial limit Velocity is u and final velocity is v. Attention take a look at ya 1/2 took out a once instead of m and v i have written v second This time I replaced v with u so it becomes u² will now be 1/2mv² - 1 / 2m u² what happened to this? it is done sir Initial Final Kinetic Energy. this u means That is the initial kinetic energy. OK sir. So Work Done By Net The Force Work Done By Net Force is equal to change in kinetic Energy Has Been Proven for This Variable Look at the force, we have proved it for the second time also I took these derivations, both are famous You must remember both, not one Both should be remembered as derivations are asked Are. take a good look at both What is the difference between? Once We use the equation of motion for acceleration I used it. I will write it in red color. Ok sir, equation of motion. and the second time We have used this form of acceleration The one with dv/dt. So don't get confused in this. why did you use it? Relatable to the Variable Force and Relative to the Constant Force. We used it with this respect. Ok? These did the derivation which we were told worked Energy Theorem. Now a good bit of it ask a cute question that You will get a feel of how we can apply it. We can apply this work energy theorem. Think Please, just understand. Do you have a question that Even though JEE Mains 2021 is the admit card for the exam, candidates can apply online through the official website jeemain.in. It is main but it will make you feel that watching it a body of a mass m same to same question I will tell you in my NCERT now mass m Drop from a height h From here, the mass m is being dropped be dropped now If so, you should keep this in mind when we drop it then the initial velocity It is zero son then initial kinetic Energy will also go down to zero Reach the Ground Height going down h distance going down ok sir sir with a speed of so much 8 in GH He is reaching down at this speed. Ok Sir finally it has some velocity It has been happening. and that velocity is given some 8 under root has GH. and the value of a Work done by air friction like this below If it is coming then who is bringing it down will be? Sir, MG must be bringing it down Force. gravitational force brings it down He must be coming. A force is applied on this particle which is going to be downwards. and Sir Air What does friction mean? see if there is anything up then the friction causes it to fall below the Relatively opposes relative motion. Meaning, it is the air friction that causes it to come down. Preventing from. Friction in reality Something that we were never counting on happens. But this actually happens, son. So In which direction is this air friction Will it take? This air blows in the upward direction There might be friction sir. so up here There is an air friction felt in the direction of Is. This is air friction. We need this air Work done due to friction Have to take it out. So first think about the story According to what I have given Modifying and Applying Your Concept to do. So the story is such that in the initial The initial kinetic energy is zero. Below By the time it arrives it has some final kinetic There will be energy. 1/2 mv².8² / will become 2 mgh. did you square it, son? V's because of this. Ok? Now look at the work in it We will apply the energy theorem. This is us can understand that sir work is done by all the Force is equal to change in kinetic Energy. We understood this, sir. but all Who all will be in The Force? so a work done by gravity will come and take it down going. and sir one work done by friction F will come which will be in the opposite direction. It seems to be in the opposite direction. These Friction F I did F. Opposite In direction. Displacement down, mg Force down, force with air friction up. It should come out negative on top. you understand I came that work is done by mg and he is positive will come. Because there is displacement below. Ok Sir? So h is down and mg is down as well. so this It will come positive. And if you look carefully, this There is friction force, work done by air Friction. That is not in the downward direction. That force is in the upward direction and The displacement is in the downward direction. So, here it should come in negative. He We already know it by feeling. Now, we write here. see, work done by gravity plus work done by friction the air friction that is there and the change in Kinetic energy k final - k initial. OK sir. Now let's continue simplifying. Look carefully. Work done by gravity sir, mgh. mgh. Work done by friction, that's it I have to take it out, sir. Kinetic Final Energy How much will it be sir? 8²8 of .8² of .8 square divided by two this will come to mgh and Initial kinetic energy will become 0 hmm Sir. Excellent. look carefully at this No, let's let it remain here. Work Done by friction this mgh one to that side They take it away. So this 0.8 is the whole amount of it. Square divided by two. Ok? ah it will be mgh. Minus it went that way mgh. look carefully Friends. Take out the common mg here 8 *8 / 2 and minus nothing from here means one Simplify it, you will get the answer in negative Just a little simplification will help this will become 04 you have to subtract 4 * 8 You have to do one and you will get negative result The answer is and that is equal to minus 0.68 you will get something something else mgh as it is Look carefully at this question Do not get confused with calculations I have told you. a little bit light There is a calculation. it is a JEE mains question Neither would be sensible. OK sir Please look carefully. these negative Although you can check the answer directly Were. According to what this logic was saying, D The option would have been created earlier. D option is already available Gets made. but also by the method of calculation You should know. So D option is You will get the correct answer. Perfect to the point even. no problem Look at this question carefully Because there is such a question in your NCERT The question I want to ask you right now is I am going to. Work Done By Gravity extracted from mghh. We had to find out the work done by friction. What did we use? Work Energy Theorem I used it and then took it out. wt means work energy Theorem. OK sir. Did you understand? Take it. This question has come before you. work Done. Where did this go? Here it is. Here it is. it Our NCERT example number five There is a question. Example is 5.2. Ok? These You have to ask the question. 5.2 Meaning Chapter It's five. Ok? But I have learned the basic Mathematics was also included, so I said chapter six. It's five. These Actually there is chapter five. Ok sir. These The story is such that the same incident happens in it Is. it is the well known that rain drops falls under the influence of this downward Gravitational force. that is a rain drop. He is coming in the downward direction. Ok Sir. How much will it fall due to gravitational force? Used to be? That height is equal to given. Ok? mg is coming down because of f. But there seems to be an opposing force here Is. The opposing side seems to be resistant. So Same story here too. one mg force feeling down and a resistive force up Looks towards. This is a resistive force Looks like an upward move. So you get your work done We have to find out mg force. And Second work done by resistive force Have to take it out. due to which resistive force How much work will be done? So what we applied I did the same exact story here as well Have to do it. consider a drop falling is this Height 1 Km. hits the ground with the Speed. See this, give the final speed here also It has been kept. Earlier the route was given for GH. It has been made even simpler in this. at 50 meters The seconds are mentioned directly. just told it straight Is. Work done by gravity in A option I have asked about the force. Resistive F in B option Have asked about the work done due to. Yes. Please write your answer in the comment section. Inform me before leaving. See this from NCERT The questions are also same as that of JEE Mains. don't do that Understand that JEE Mains is an upper level. No Look, this is a JEE Mains question and your See the NCERT question. But One has to write in detail here. over there Calculations have to be done quickly. and this This is how calculations are done by JEE Mains students that whoever wants to do anything can be done easily It is like that only. Do some calculation of your own NCERT ones are sometimes difficult She goes. The language is a bit harsh sometimes It becomes difficult. Ok? You can answer this Write in the comment box. Tell me that this Did you get the answer or not? ok golu Brother, write in the comment box and then you will know It will be alright to know whose answer was correct. From whom all this question could be asked? Ok Sir. The story was about the work energy theorem. See It's in the work-energy theorem, right? many of The work was done because of such forces that Work done will never depend on the path. Like gravitational force. Gravitational The work of the force is done, it is never on the path Will not be dependable. Like I did this pick up the bottle from here and put it on my head Gave. Ok? So the work was done by me. I got some work done. and gravity I did some work against him in the field Isn't it? so work done by gravitational force Always The bean arrives. For whom will the beans come? Like this bottle was here. I picked up the I kept this first. Work Done By Gravitational Force. First process. then look at the bottle here But it is. first i did it like this then like this Took it. Then I placed it on my forehead like this. Work Done By Gravitational force for this story. Correct yes sir. then see the second story i have bottle It's here. Now do it in a circular motion on the forehead I kept it. Work done by gravitational force In the third process. In these three processes, Work done by gravitational force is coming That bean will come. You can calculate it. I will also tell you the method, how to calculate it. Sir It's a simple matter. Work Done By Gravitational Force. mg is its mass. mass mgh g its Force will be applied. mg force applied downwards It will take place. And in every process you go from here to here You are taking it till now. So mg h will come in minus. mg downwards, h upwards. So in the minus mgh in every process. So, dependency on path There is not even a little bit of it. So such forces that Whose work will not depend on the done path. In simple language. such forces whose It will not depend on the work done process, It will not depend on the path. just the initials Situation, final situation. Initial situation, Final situation. It will depend on that Work done. Such forces are called conservative forces. I will say it. Its opposite definition will become Of non-conservative forces. Our Syllabus as there is gravitational force in is the spring force, the electrostatic There is force. These are all conservative types There are. OK sir. so in short its The definition will be given such that a force Conservative if work is done by that force is Independent of path. I mean we tell a story Moving from A to B for . Then, There were many ways to reach B which were not possible earlier Someone went up path one, something like this on path two Went, Path Three went something like this. This three Work done in these three processes in the process for path one which comes is equal to work done by second work done by second and same equal Two Work Done By Third Work Done By Path Three. This work done is equal in all three cases Used to be. It is coming equal in all three cases. So We would say that whichever force here Because work done is written that force either Gravitational force will be either spring force will it be electrostatic or the other It can also happen. But this force is conservative It would be natural for its energy not to be wasted it occurs. This energy is stored somewhere will go. then the effect caused by such a force Work done is stored somewhere. Energy It does not get wasted. Somewhere Potential It gets stored as energy. Well then Sir. According to our syllabus there are three such There are forces. There are three such in our syllabus forces, one of which The one for electrostatics is the one we are in 12th will read. electrostatic wala hum 12th I am going to study. But remember this Son. This is its special feature. Work Done By of the Conservative Force. same to same The question was asked once in NEET 2021 tell me whether gravitational field is present in this region mass is shifted from a to b through the different paths hai shon to w1 w2 w3 different different work has been done by this Gravitational force so work done for this How will it look, it usually looks like this that displacement work done into force into See displacement here even if the path even if the paths are different even if the paths are different But sir The initial and final position are the same Is. The initial and final position are the same It's just beans. It is same to same. It means a The option will be correct. W1 = W2 = W3 Work Done By the talk of gravitational force came up. These Son, you may get success in MCQs. good to this Write in a proper way, understandable. Now a proper I give the difference because our Such theoretical questions in the examination It turns out that gravitational forces are conservative Between conservative force and non conservative force Tell me the difference. So remember that work is done Independent From The Path. on the path of this There is no dependency. This dependency on the path Not there. its independent from path while It is a non-conservative force, it depends that for whichever is the longest path You will get more work done. ok sir work done along the closed path is Seeing zero, seeing an incident, this initial position We go around and around and around and back again If you reach the same place then this is your final position Initial position and final position are same displacement will become zero If displacement is zero then what is the use of work brother what work is done if the path is closed Let's talk so that the work is done Gravitational Force Work Done by Spring Force Work Done by Electrostatic Force or Work Done by Conservative Forces. If I If I want to tell it in a common way then this For closed paths like this one is known. Ok? This is coming back. so closed path will become zero for. work done boy work Done for closed path this will become zero. Here is something for the conservative forces: It does not happen. Not equal to zero. Non This does not happen in Conservative. Opposite That's it, son. Ok? this is it na State function. This is called straight in fancy name The function will be called that does not depend on the path. it's just an initial state and a final state It will depend on pay. this is just the initial position And it will depend on the final position. this path It will not depend on pay. Initial state and This will depend on the final state. OK sir. So son, dependency on initial and final It is his. So work done by closed f = work Done by conservative F = 0. If If there is a closed path then. So it is straight forward that This is known as the state function. While this is a variable sir it will depend on the path Pay. then force can be velocity dependent Regarding the nature. that will depend sir Which force of nature is this? here we are like this Cannot make assumptions. Although these variables It is possible Here the state function can be Is. Straightforward state function. Ok? which here The energy that is in the energy conservative force Whatever happens is not wasted. somewhere sound energy in the form of such heat energy She will not run away anywhere in the form of. These Energy gets stored. of that position The energy store for that configuration It happens. which we can go ahead and call potential Will also talk about energy. So the energy remains here The constant where energy is dissipated Is. Sound energy in the form of heat In the form of energy, resistive energy In form it goes into the waste form Is. Like friction force is conservative There is friction whenever you talk about conservatives Remember the F. due to friction force Energy is wasted. and here you are If you are thinking of conservatives then Remember the gravitational force. Gravitational Remember the force or the spring force. Because in 11th we will study gravitational field And we will study spring force. So these two Remember this. OK sir. the whole thing here work done is recoverable that whatever Work done is converted back into potential energy That's what has been stored. so recovered it May go. There is no such recovery here There is no recovery system. These There was talk about non-conservative force. Attention See it from here. This is a question of two marks I can come in. And I know by then your This will come in the examination or work energy Of the theorem. So a derivation like this can be asked Is. This was the conservative force and non The difference between conservative forces. So Due to the conservative forces here, The work that is done would be stored somewhere Is. And how is it stored? in which form Is it stored? These are potential energy It is stored in the form. So any position because of or because of confusion The energy that is stored is called potential Energy. yes sir. So the conservative forces in opposition listen listen listen villagers what The point is that work is done by conservative forces Work caused by conservative force Done and the work done opposite to it That is a star in potential energy. Potential energy is expressed in the form of delta U I write. because this is actually The energy we get cannot be converted into Potential energy is obtained. We define They change into potential energy Let's define whether or not you're single Potential energy. means any one point Or it is not about position. that one The full potential of configuration There is energy. That is the potential for change We define energy. so work done by conservative forces opposed to him Work to go. that is, it is a store will go in the form of potential energy. So We got a mathematical form. Look now It is a simple thing son, which one is better at any height Which water is more dangerous, this one or the other? This one is going to happen if you fall on the water to swim You won't be coming back anyway though Understand this, if water falls on your forehead then There is no problem here, down below my head No, it means that if this is the case then even by hiding like this you You can take it with your head, the water here is not dangerous but the water above is there if you stand below yes and the water came with a splash from above There might be major damage, then the above water has a little more energy And what if instead of water you misunderstand a stone? Look here, there is a stone down here, this one is so high It's a stone, it fell on my head, nothing happened But there is a small stone at this height So small but now it goes on the stone It will fall and you will be below, it will be a very bad situation If someone goes to some height then he will get a stone or something if there is an object then it has some more He has energy only then he can do big damage Is. So this means that this is a It's a game of configuration that more There is more energy at height and that energy It is called potential energy. it is called gravitational potential energy Is. So we study two in the syllabus. One gravitational potential energy which is the height of We are majored more because of our in the syllabus and the second one i.e. Spring Potential energy. You did this in your childhood Did you play with the toy or not? Once Write in the comment box. use this toy I must have done it. what would be its mechanism Is? Even if the Chinese were Chinese. Indian Such toys also used to be available. but sir is like a stick We used to shoot like this from behind then A spring used to be pressed here. That Energy was stored in the spring and As soon as it was released the spring gave away its energy hey brother i have a lot of energy yes satak Energy gone from here. This is why it is running away Was. This is why this bullet is missing Was. Why? because as you pressed something had worked. In opposition of whom? this spring Did some work against. And these tasks potential energy used to be stored In the form. As soon as you let go, this energy Released in the form of kinetic energy. So sir, Energy is being stored here Form of potential energy. So our According to the syllabus there are three types of subjects We read Conservative Force. One a Gravitational force, a- spring force, And an electrostatic force. and these Potential obtained due to all three We write energy as gravitational Potential energy. Elastic Potential Energy i.e. spring potential Energy. and the last one i.e. The electrostatic potential energy, which is Will be studied in 12th. Light definition Is. Read it once. we wrote these things It has happened. that's just the way it is potential stood in this object due to Earth's Gravitational Field. Ok? then it is The Potential Stood in Object. it is Deformed state. means if it is spring So any deformation created in spring like if I change its length Should I do it, I have done its length, son Very small. So, there was deformation in it. Or Then I increased its length. Look at this I elongated it. then its spring shortening the length of a part due to deformation I gave it to you, pressed it and pulled out the length in one go like this To spring. So there is no energy source here. which we call elastic potential energy or spring potential energy Are. We will study these in details in 12th. what is electrostatic potential energy it occurs? but lightly you know Should be. Third type of potential About energy. Now let’s understand What is gravitational potential? Deep Let's read Down. See. so straight talk any tower eiffel tower sir we Sitting down here. We have mass end superman the block from under the superman bun No, leave it, I will use the local one. We Suppose you have become Balveer. Baalveer You have become Baalveer by hiding. hey down This happens. Ok. There is no hair. Is this a curtain? That one is red in colour. Ok. So on Hirani I am seeing this power. So what did we do? Mass we will fly and hit the ball of m together have been taken up. hey why take it up Are you? If Balveer is there then we are together in the air They are taking it away. if it was a simple human So I would throw the ball up like this. I would have gone away. But we are becoming Baalveer, right? So this We take a ball of mass m from bottom to top Height h at. We took you to some height Are. Its mass is m and what is its height? Above We took it. we went up to h height so You are the work that Baalveer must have done Have you become Balveer from Golu Bhaiya? That's it sir h if you have taken the height up How much have we fought against the gravitational force Work must have been done or gravity might have done it how much work would have been done sir force mg It may seem like its up and down direction I am yes sir and you are taking the height up Let the angle between the two be theta = 180° then cos theta for this case = 180° If it becomes -1 then mg moves in the downward direction In direction. OK sir. H is up The angle between the two in the direction cos It will be written as 180°. then this will become minus in mgh. OK sir. Look carefully sir. Change in Kinetic Change In it was written that potential energy is equal to Negative of work done by conservative f. And Work done by conservative f means what? Gravitational force. Yes sir. Now How much gravitational fee did you get sir? I got mgh in minus. minus minus + mg. However, it is true that there has been a change. means that u The final -u initial has come. but what if If I set u initial to zero in the initial itself Should I accept it? We assumed that where So I'm calculating it for myself A datum point will be created. This becomes a reference Will go. What will happen? become a reference will go according to this reference frame Initial potential energy I has zero value Took. So this becomes zero. so final h height The potential energy I'm getting from That is mgh. So the gravitational potential There is a very simple funda of energy that h That energy required to move up the height is = mgh. Somewhere according to the reference frame you Must consider it to be zero. which is the majority of the time We call this a datum point or reference point. It is said that where the potential is zero. So simple story h you will take your height upwards mgh. h you will bring down the height - mgh. Here's work done by gravity. His Opposite means negative sign will be written. it How did you come? I just told you this. Here But I told you. You have to remember this, son. this memory Have to keep it. This is a very important form. What Did you understand? Look carefully, friends. Are you able to understand this? we we Ok. This was the gravitational potential Energy. h when the height increases mgh. h height On coming down - mgh. OK sir. Now look at it It will be more fun if I ask questions. Little Stop. First Spring Potential Energy I also teach it. Mostly we used spring I haven't read it. but still remember once I will get it for you. Maybe you read it in NLM You may or may not have read it. If Spring Was Called As It Is It is placed where any spring Deflection is comfortable at its natural length On the situation. so x displacement is nothing, Spring force is nothing. But when this is done using x is displaced, elongated is then squeezed or compressed. This Look at the story Elongate Elongate be It is being or it is being compressed. Compress is done. in that story son Some spring force is developed. Here But look, we have displayed x as positive Side. So x positive. But here the The spring force will be applied opposite to this Is. That would be proportional to the displacement Is. But it happens in the opposite direction. So this spring force returns back to its original state He is trying to get into the states. So This spring force fs is installed. These Spring force fs is applied. Displacement fs is installed in the opposite direction from. Here But you tried to suppress it. spring The force will be applied in the opposite direction that I I want to return to my original state Am. And it always happens in pairs So I represent both ends. Am. Ok? So sir this needs some compression if you try to elongate and if If you compress then try to elongate Let me see, fs is positive here. Yes. So The formula for spring force is based on Hooke's law According to us we get it. will keep constant k. So - kx it is the form of spring Force. Now brother we have been asked whether Potential energy is required. The force is ours I already knew it. might already know yes. So how will Sir work done be written? So Sir short for work done, work done. One thing Tell me is this a variable force? Yes Spring Force It's a variable force. Its dependency is as much elongation as it is The magnitude of the force is higher. As much Magnitude of compression force More. So this is its dependency on x Son. So the variable is quantity. thats Why we will integrate f spring We'll integrate into dx dx. Memory Keep. And this spring force that we get Work done due to spring force will be obtained You will get its negative i.e. stared in Potential energy. So we just do this thing first I am writing. See how much spring force Did you come sir? - in kx - in kxdx Sir - k we took out x.dx x.dx sir will you integrate x² / 2 ok sir look if x = 0 value and x final = x value Here you go Sir ji work done by Spring The formula will become 1/2 Minus minus came out. ok sir 1/2 1/2 kx² in negative if you want it to be x Also write in the form of initial and x final You can but I would assume the initial to be zero. I am going. So 1/2 kx² Ok sir. Now Sir you have to take us out of the system is the change in potential energy. then change is the negative of conservative force and Here we have the negative of spring Force. yes sir. so the negative of spring 1/2kx² in force minus minus minus plus so 1/2kx² we will get spring potential energy What? Spring potential energy is written as Will go. The initial one is also written here Depending on the reference frame we choose and write the initial one as zero Can be done. But I wrote it directly took 1/2 kx² it is the form of Potential energy. Spring Potential. Did you understand the formula of both? Formula for both. This is according to x² It is written. While the gravitational potential It was, it is written as mgh. Reason for height It is from. This is due to some pressure sir. due to the spring potential configuration Is. Are you understanding things? Spectacular. Now its even better and more amazing ones Let us ask questions. One of NEET 2023 There is a question. Relatable to Spring Potential Energy of a Long Spring When stretched by a 2 cm. is you. If I am a spring then give me 2 Cm. if I pull it, then this potential Energy can be written as ui or u directly. 1/2 that x² means 2 cm. Square. Now If I stretch the spring by 8 Cm. till. tuck 8 cm If I stretch it till then this What will be the final potential? this neet 2023 I asked the question. u'=1/2kx=8 Cm. For this story. So 8 cm. Of Square. Look carefully. Eight. Can I Can I write eight like this? k = 4 * 2 Cm. Square. look carefully Friends. 1/2k I made it 2 cm. to as I write it is. I will take out four And I will square it to four. what is this thing will it happen? Sir, this will become U. Then, U' = 4² and this will become U. So U D = 16 fours fours 16 u ok sir so the correct answer It will come, write it in the comment section, son Also 16 u will come with me D option The exact answer will be generated instantly upon seeing the question Go and understand it if there is any confusion Keep asking son should we move ahead or have another meaning because it has potential energy in it Spring Potential Energy Maybe for You it cannot happen otherwise you are the majority Do you read the gravitational one or not? Only then will you feel it. Wait a moment. Just one more Concept then its questions are good I will get you to ask more lovely questions I will get it done. So the first one is a little concept. The work-energy theorem is a smaller sister of the Because it is called COM. Low C O ME In the beginning I wrote Come C O ME C O M E Conservation of Mechanical Energy. Many times it is called CO in short ME. What to see is that Total Mechanical energy of a system It remains conserved. when just and only Only conservative forces remain in that frame In. In that system, then. what did you say Sir? Did not understand anything. They did this He said that if the kinetic energy in the initial plus the sum of the potential energy, that is Mechanical Energy. Mechanical energy can be divided into several Also called total energy. So, total The energy that is there initially, remains the same Total energy will finally remain the same. that much Total energy will remain finally. Conditions Applied If there is only conservative force. any friction or any resistive force This is for the time when it is not there. ok sir look How is this energy conserved? What does it mean What happened? to ti initial = t final. Its This means that k initial + u initial = k final + u final. Sir this is total energy As much as the system had at the start That much will remain in the final in the final. that much will be in the finals. When is this story from? When Any resistive type of work resistive type of work Don't get it done. There should not be any resistive type of force. There should not be any friction type of force. only and There should only be forces and they should be conservative forces. Then have you ever sat on a roller coaster? There But this is what happens. Though friction The force is there but in the ideal case that if we talk then look at this at some height The maximum potential energy is The one with gravity. Then he came down with a thud It gets converted into kinetic energy. then the kinetic energy maximum here below Reached kinetic energy maximum. with a bang as it reaches back up again this kinetic energy is converted into gravitational energy She goes. so in short kinetic energy Gravitation means kinetic energy gets converted into potential energy. potential energy into kinetic energy convert, this is how the rain would convert It remains. from one form to another It will be converted. But it will not be wasted. If there is no resistive force. Any move a ball or any object from top to bottom Drop it. above him at h height There was gravitational energy. as soon as left Sir gravitational energy got converted in kinetic energy. Coming here my Coming to the left hand side, it has some Velocity must have arrived. What magic is this? Energy potential energy is here. Below I. it gets converted into kinetic energy Went. What an amazing thing sir. So one of this There must be some proof. Because we are Sir Even though I am a student of Physics, We are also asked maths questions. and we have to do JE or NEET or any other small CBSE exam questions also have to be done So maths is only required Just such tall talk will not work. Take I will get it proved sir. See have we seen the work energy theorem, Have you understood, thought, read? yes sir. work Energy theorem says, work is done by all the forces is equal to change in kinetic Energy. Is this 100% true? These It is 100% true for all the cases. this is 100% It is true. 100% Work Energy Theorem 100% It is true. Yes. Ok? I have written it down. Ahead Tell me the story sir. what is done by all the What can happen in the forces? Think just. Sir may be a conservative force. There may be conservative type of forcers Are. There should be conservative type of forces Can be done. Plus non conservative type There may also be force majeure. Non Conservative plus external ones too Can be done. Is equal to delta K. Ok? I divided who is who in all Can be from. Conservative, Non Conservative and external. Suppose two Condition. what is it son? Two condition values Take it. By doing if I write that if non Non-conservative due to conservative forces The work done due to F is zero Is. End No external force should be applied Used to be. So that is also zero. The external also No force is being applied. So Only whose work will be done would cause? Only the work that is done That work will be done by the conservative force would cause. both of the other two are zero Will go. both of the other two are zero Will go. Then only work would have been done Is. That will happen because of conservative forces. will be. and that is equal to change in Kinetic energy. Look, here we have two I accepted the conditions, son. These two condition values For. Our answer for this condition is He will come for these two conditions. Attention View from. We are working on these conditions. OK sir. so sir ji work done by conservative f to We represent this by delta U. Yes Write it down. And we know this in any other story Is. I just wrote it. Work Done By Negative of Conservative Force = Change in Potential energy. So we did negative u Gave. And if there is any change in anyone else, what is that? It happens? u final – u is initial. So u final - u initial = k final - k Initial. k final - k initial. From here If you leave the bracket and open it, then u will be in minus final + u initial = k final - k initial. yes sir. The one with k initial will come on this side. Then k initial + u initial = k final + u final u final what does it mean sir The initial mechanical energy will be equal to mechanical energy will be final will be equal which means energy is conserved Will the energy be conserved? Mechanical energy will be conserved if If this condition is satisfied then be careful Have a look. This is 100% true. but below the form that we have written or this one The form we have written is not 100% true. comes with a condition which you It should be kept in mind that any non Conservative forces are not here Needed This proof is also asked in these forms of derivation. in the form of derivation this are asked. Write it down carefully Good thing. In a good book, from a good place It will be fine if the book is not good. But It is essential to write intelligently Son. The story was this conservative Conservation of mechanical energy. Now I get you to ask lovely questions so that You will get the feel of it. we'll think about it as well as whether any non-conservative Was there force in it? Thinking. What is the story? The first story is before us, Sir, consider a Situation as shown in figure. look at it first We have to think and understand the situation. Ok? CBSE PMT is said to be like NEET This will go to him. a spring a spring of a The spring constant whose spring The constant k is given as equal to something. Its The spring constant is given in the story. The Spring Constant Story of This Spring I have given it in. OK sir. the story ahead attached at a one end of a wedge rigidly with A horizontal part. Rigidly with it This spring is tied very tightly To. OK sir. sir a 40 gram mass of a Released from a rest. I have given its mass It is in the story. This is the one that is kept on wages The mass of the block given to us is 40 grams. We will convert it into kilograms when needed. It will be needed then. Ok? Ok? this is its height 5 There is a meter. Ok? and along the curved rake Minimum Defection Force Minimum Defection in a spring is near by means of spring How much do you look, think, think, think, think. Think about it, what will happen? It is near it right now What is? This is the initial situation. this is its This is the initial situation. this with a bang as if If its kinetic energy is dropped then It is zero. But it is at some height here So at any height it has a potential There will be energy. And what is that potential energy? will it be? The gravitational potential energy It will be in the form. so this gravitational Potential energy will be written as mgh. What It has no initial kinetic energy will it be? No sir, he is on rest. Ok? These came with a bang down down down down down so what about down there, its gravitational The potential energy will be converted into will go in kinetic yes sir its velocity This short spring will become very high will collide with and this will cause the spring to if you try to compress it, will one Its velocity will return to zero in time yes sir this happened in final situation at one time Its velocity will return to zero which means because we can write it back Velocity Zero. Because of this, the kinetic energy Zero. And when it gets compressed then this in the whole system in this whole system You will get strong potential energy. End That's the constant potential energy equal to 1 / It will become 2kx². that the compression was x Is. x is the amount of compression that has occurred. I understood it In? Potential Energy at Initial The gravitational one. It went down the drain. If it is dropped initially then there is no kinetic No energy. Came down till here. of the whole All the gravitational energy is converted in kinetic energy. then this velocity He ran away in unison. Now all of the What did the kinetic energy change into? in spring potential energy. So, this The whole incident, I am just talking about the initial and final I have dependency on you. Because Applying Conservation of Mechanical Energy I am from this party and there are conservative forces in it. So I am just going to apply HUM C OME. Final from Initial Position In between positions. anybody here sir There is no resistive force. Any friction It is not a matter of that. Any air friction It doesn't matter. and any external force There is no question of that. Then KI + UI = K Final + U Final. if you look carefully The potential energy stored in the initial Thee, it is the form of gravitational force. it is the form of gravitational Potential energy. and finally the potential energy is the spring potential energy Was in form and kinetic in the initial stages too Kinetic energy even in Energy Zero final If it is zero then there is nothing to worry about. It will be written simply. mgh in initial some height h i.e. 5 meters and finally This is 1/2 kx² of deformation that was taking place in that spring. OK sir. then we have to 40 grams is given in the question. 40 I can write grams as 40 * 10 to The value of power-3g will be 10. of h Value 5 1/2 as it is. The value of k I have given 400 in the question. OK sir. and x We have to find the value of . Simplify Tax Can we? yes sir. can sure We. So, simplifying a bit, we get 4 Give it away, this will be done. two comes up 10 10 100 so He died and along with him went three more Midu and Its two midus are fine, if one dies then four more here 400 x² will come, if we do the calculation then this will become one 1 / 10 1 / 100 = x² = of x square will be we're okay so x's From here the value will become 1/10 centimeter See if my calculation is correct My cal calculation is correct. Centimeter From where? It will come in meter, right? this is in meters will come. If we come in meter then convert it If I do it in centimeters then it will be 100 Divide by 10. This is now in centimeters Will go. So each one gets cancelled out. Approximately 10 cm. its answer will come. Simplify it a bit If we go by the approximation then it is 9.8 Cm. The answer given will be correct. meter Km. Where will I come? 9.8 cm From 10 This must be close by. It will be close to 10. yes Can play a game with G value of 9.8 yes. but i took 10 so answer Exact 10cm Came. Actually 9.8 Could have come as well. Did you understand what? You won't get confused, son. Good It was a question, it was a lovely question. This If you don't understand then go back to it in a calm manner Understand it, count it because such questions are asked You go and check your CBSE, your NCERT I have such questions. You might think so Sir So what kind of exams are you conducting? Are. Such questions are being asked In different types of examinations. They are coming to NDA as well as NEET yes, he is also coming in JE and his Coming from NCERT. So I first I am showing you that the questions outside are easy Is. NCERT questions are even difficult I will meet you sometime. So let's understand together Remember this isn't just about one book. There is talk of many examinations here. Ok? Then option B would be correct. Exactly one more The question before us is that a mass of A.5 kg moving with a speed of 1.5 metres per second. Colloid with a horizontal smooth surface We have a nearly weightless spring and whose value of k is also given to us in the question I have given it. the value of k for which we get It is given in the question. ok sir spring Constant has been given. The Maximum Compression of the spring wood be how much compression Will he come? Hey, think about it, brother. what is this Story? Sir initial it has some is the velocity. Ok? These are the values in the initial Let u be the velocity. This initial situation This is the initial situation. See any one Would it have gone with velocity? Its initial The kinetic energy will be 1/2m² Yes, what? It has no potential energy sir There is no compression in it right now, nor He is not very tall This incident is happening at the level as soon as this The ball will collide with this spring after that there will be some compression we sir some If compression comes then I will do something I accept it as my responsibility tudu tudu tudu this is something I assume that this ball comes here Went. some of it has been compressed x As much. So this became its final arrangement. So in the final arrangement it looks like this will compress the spring will I will do it and maximum at one time Compression will occur when its velocity is zero She must have gone. hmm sir. So Final Kinetic What will the energy become? Zero. and finally The potential energy it will have is 1/ will be in the form 2kx². Is this whole In the event there was any non-conservative force what son? No sir. No resistive force, No friction. so can we right come According to COME, it is a conservative force Here. So Kinetic Energy Plus in Initial Potential energy = Final kinetic energy Plus potential energy. In the initial Kinetic Energy 1/2mu² Sir. Initial potential is nothing yes sir final kinetic energy oh nothing sir final potential sir is 1/2 kx² we sir Simplified a bit 1 / 2 1 / 2 cancels out mu² = kx² mu² = kx² of m Is the value given in the question? 0.5 kg? yes sir. 5 Although I love its formula I can make it too. see x maximum compression Equal to, look carefully friends. it comes will go under the route of m / k and u I will take it out, it will become u. The value of m It is given in the question. ok sir what is v The value u has given, this has been given sir and k The value of is also given in the question. Just put all the value answers Take it out. Tell me in the comment box who This ans is correct. tell me a b c d a b c D A B C D means a little calculation I have to do it, son. You can do this much work yourself Is it for your master or for yourself? For. will you do it? will you solve it? so answer You will get 0.15 Meter is the right answer. This answer will be correct. Now look, you are wondering this question, right? Asked in CBSE PMT 2004. So much All the old questions or so many examinations Why are you asking questions? Own Read a question from NCERT. Question Number eight is for example. This is from NCERT. Read it comfortably once. Its language Understand. Then compare it with this. this question To compare with. ditto to you ditto It will take beans. Same to same question. Who The formula I just applied is the same The same formula will apply. but first Understand the language once. to the situation understand. Then find the answer and comment Let me know in the box. Ok? this work Yours will be on priority. right now right now Pause the video, Golu Bhai, don't look ahead. Pause and write your answer in the comment box. They It is necessary first. will rise again. be careful Look Golu bhai, did your answer come in 2 meters Is? If 2 meters is shown, then it is the correct answer. If it hasn't come, then think what is your mistake You have used Nickstick. Ok. Now look at this We have considered gravitational potential energy and In the base of spring potential energy I have asked questions. Now Pure Gravitational energy gravitational potential energy and A little bit of NLM i.e. Conservation of Linear Momentum PCLM Principle of Conservation of linear momentum from both of these A connected concept i.e. vertical Circular motion. a very small In questions I have seen this vertical circular The motion has been broken. Vertical Circular Motion meaning a bomb hanging from a length of rope has happened and we call this vertical circular motion Trying to get it done. so sometimes this We will ask about velocity at this point, sometimes I will ask about it, I will ask about the tension here sometime. All these incidents are just a few of the small examples I will explain. Small questions. Any Not a big question. Small questions We will give you your field. So look In the initials this mass m is some boob which This S is hanging in place and has some initials on it Velocity is being given by VA. so the question is this that is find the minimum VA for this bob just Reach at a point B Reach at this point The minimum velocity to reach B is How much should there be? Understand, friend. here at We assume in advance that Sir Initial The potential energy is zero at this position. Or we can assume that it would have happened our way Is. We are taking the reference, that's why Son. So we took this reference that zero it is at this level. This is a determination for us It will become a reference for. u = 0 Now, carefully I have to understand. from point a to point b you have arrived and just getting here What will be its velocity? at a point B Zero. The event of arriving just is that just Touched it and then came back. means it is like this Motion will do. Look, my hand looks like this Shru Shum shum shum happened completely horizontal like this. Then I am back. Shum shum will make some motion like this. This is the length l of the rope. of rope It is negligible mass. It is very light weight. Ok Sir we have to find the velocity at a point A What should be the minimum? Can I using conservation of mechanical energy for a point A to B according to me You can do it with. because the initial position It is A. The final position is B. Initial Position There is no pay potential energy and the final There is no kinetic energy at that position. We The matter is interesting. Let's solve it once Are. why not sir? Because the initial in level we have called zero that that reference Potential energy for the level is zero. And When you finally reach point B then the velocity Zero. This means Potential Kinetic Energy Zero. Kinetic Energy Kinetic At point A in the energy initial. then 1/2 va² mass took m of it. this l height up He will go away, see. Gravitational Potential What does energy say if the mass m is l If the height goes up then it will have gravitational potential will become mgl then V can i write it's a mgl can i do it from both sides He will die, he will die if he goes in that direction we will become equal to sir 2gl in 2gl its value will come. no mistake, no problem, any solution? Oh no sir that's right It seems that the minimum velocity should be this much Needed Then it goes just till point B will reach. If it is just more than this then let's go It will go only. But there has to be this much velocity Needed Then it will be on the horizontal level will go, will reach point B, otherwise Will not be able to reach. Great, no problem In this. Look, if he goes that way, mm will die. So, two went that way, under root 2gl answer It's here, it's over. if it was square then take the root Is. Ok? First question, second question. Now not B, now take us to point C Is. Now we have to take it to point C. What will be the conditions then? how much minimum What should be the velocity of A? in this position of. So it is a little bit difficult to remove it. It is a bit difficult. It takes a little brain There is need. Just imagine if this rope is C What are the conditions to reach the point? will it be? Just reached the sea point. just just Just's stories have arrived, yes all of Just This is the whole story. Sir, somehow in a way that this rope reaches here this bob It should reach till. Ok? When you reach this bob then be careful Let's see, there might be some velocity behind it's VC Here. but in this rope Then the tension instantly became zero There won't be any problem either. means just that The condition will be that upon reaching here If its tension force becomes zero. See Force was deployed here as well. Tension t the force upwards downwards mg which is a were balancing out the other one and this Tension - mg = mv² / r This is what was being formed, right? mv² / r This was the centripetal force. Yes Sir. mv² / r then its nlm will draw c look at the point, it will be made like this below Tension in direction. OK sir. By plus mg will be in the downward direction. and if If I look carefully, son, this is the centripetal Playing the role of force. This only Playing the role of centripetal force Are. so m these f centripetal I'm looking from the ground so Centripetal spoke. if in this frame If I sat down, I would have said centrifugal. So Sir t + mg = condition of centripetal and just This will happen, son, that the tension force should be zero let's go. mg alone will balance it out. This It will play the role of centripetal force. Just mean the rope could be slag. Rope There may be slag here. what could be Is? The string will slag. string a little C will slag for a while. and slag means The tension force will become zero at a point c Tension at a c point g = 0 then mg = mva mvc² Divide by its length will be l The centripetal force will be written mv² / l if If we simplify it a bit then it means VC The value will come from here under root in gl So sir the value of va is not found but We definitely got the value of VC. VC's The value has definitely been received. The string slacked a little. String Slacked a little. Ok sir. a little bit We got more conditions of string slack that at a c point we get the tension force It will go to zero. A little slack will do just fine To reach out, reach out. then this rope Is. the velocity of that bob of his he brings it down She will take it away. So complete circular motion Will be done. Yes sir. So this is just a condition For there is zero tension. FBD we have done it well of the draw. So here FBD is used i.e. That of NLM. Use FBD properly Happened. I don't know. revise a bit Son. in fbd class 11th laws of motion This is a matter of study. Great sir. This happened VC = Under It is a bit difficult, son. Sir C's name was removed No, the velocity took you out at point C. We have to find the velocity at point A How much will this VA be? This has to be taken out. Little By using our brain again and again we can do this You'll find out, son, that I'm between these two So there is conservation between these two I can use off mechanical energy. C You have to reach the point, right Sir? We are at C point Pay. So let me remove this for C point. I take conservation to reach at point C of mechanical energy that I can use There is no external force. Then, For the story upto C I am talking about Conservation of I will use mechanical energy. Then, KA + UA = KC + uc see Kinetic Energy in Initial Sir 1/2m VVA². Potential in Initial We said energy was zero. in the finals Kinetic energy 1/2mc². See how much potential energy is there in the final Will she go? Sir, I had taken this height. From here This l up and from here back l up so l + l 2l sir mg and this 2l From everywhere I kill mmm and I will kill 1/2 1/2. means 1/2 mm 1/2 here But m died and multiplied by two. Two on that side, means two everywhere I put two If you say that you multiplied it by va² is equal to is equal to the square of vc plus 2 there was two here two will become four yes sir its 4gl 4gl vc how much was it sir vc value under root I had gl so if I square it it becomes gl will become gl + 4gl this will become even and become 5gl This will become 5gl under root its answer. meaning that just to reach a What should the velocity be? in under root It should be as much as 5gl. this velocity must Is. There should be this much velocity under root in 5gl. Then this completes the circular motion will be able to do it. Son. this was the condition for a for a Completing vertical circular motion. This Also called critical velocity. Who We met her at Sea Point. This Also called critical velocity. of many In books it is called critical velocity It is known. Critical Velocity. this little slight derivation Was. Look at this and understand it, son. cutie It was a small thing but this vertical was a useful thing of circular motion. Now you can read NCERT You can ask questions. See, vertical Circular motion is made up of just three phenomena It has happened. It is made from only three concepts. One conservation of mechanical energy which is I have read it from the chapter. we will read another one PCLM. not even pclm here NLM is being used. Also PCLM No. of FBD in NLM Laws of Motion Part is happening using FBD and a little bit The concept here is centripetal centripetal or centrifugal you Whatever you want to say, it is being used. these three If your concepts are strong then you will get somewhere We can also calculate the value of tension here yes. Like we need to release the tension here. This Tension has to be released at point A. see i Let me teach you one. After this you can also do the second You will be able to do it. If I feel tension in this case The value has to be found out. what sir? what sir? What? If I am tensed for this case The value has to be found out. tension at this point I have to find the value of . look remove this Everyone. The value of tension has to be found out in this a For the point. hum sir this a what up Are you feeling stressed about direction? Yes sir. TA in upward direction. mg down Looks like it's in direction. Yes sir. still Which direction is its final acceleration Will I be there? It will be in the upward direction. Yes Yes. It will be in the upward direction. so like this can be written as In which direction will the force be? Sir this is In the direction mv² / r this fc = mv² / r r means its length is radius l. Correct Is? So tension ta - mg is playing a role of A centripetal force. tension ta as it is Written - mg and f centripetal i.e. mva² /l will be written. v² 5gl or 5GL under root then m/l under 5GL then it will be written as 5gl + mg It's good. It's good. From here LL died LL died. 5mg + mg then the value of TA will be 6mg 6mg good sir. I am understanding these things In? Now I give you a question be careful. Yes, I'll give you a nice I will ask the question in this. This gives you to me Tell me that at point A I have to tell you about all these points A, B, C, and D. is velocity and we have to make a table that means How much will the VA be? What will be the VB? how much is VC will be? What will be the VD? and at that point How much tension will there be? What is the tension B point will be? What will be the tension at point C? Tension How much will it be at D point? These comments in HW Let me know in the section. this is what you find Can you do it or not? Look at this, it's the lovely things about physics that you Using previous concepts together Yes, that was from the previous chapter. Otherwise, go ahead Part, part story from behind. By the way all of it Let's move ahead. Physics to old friends, Old chapters, old concepts I never forget, son. So, this story Let's see who can do it. Write In the comment section, these V A, V, V C, V V D and T A, T, B B, T C T D. Critical Circular Motion or Just Completing Circular Motion Just Completing Vertical About the cases for circular motion Tell me the information in the comment section. Ok? Let's move on to a dangerous topic That means power. What is the feeling when you hear it? Power sir. Power of Bahubali is the greatest power It comes in large amounts. Bal also defeated Laldev Gave. Power Power in one way how much work is done It is being done on time. so it is a rate Off work done per time. a small definition that You read it in your childhood. as it is rate of Work done on time. So a simple formula This shows that if I average the power While I am writing, work is done divided by time. That's it sir. This average power is divided by Time. That's it sir. The unit of work done is is joule. So its unit is joule per second Will go. And its volts are also many, many times Bar what? It is called majority vote. So That is also a unit of power. and 1 hp 1 Horse power is equal to 776 700 46 that is it. remember this a little Take. In horsepower you get many times some He must have given me things. This would have given power Because of. Where is the power? Instantaneous The form is also written. Power Instantaneous = dw. Small Work Done Divide Bye short time period. should i write to dw Can I? Force dot displacement. Yes Sir. Force dot displacement in divide Short time. This is called ds/dt Velocity. So another of the instantaneous power formula sir power instantaneous equal to two Force * Velocity. what's the matter sir? Two We have the formulas of power. and power sir force dot v means this is also scalar There will be physical quantity. How will it be? Scalar It will become a physical quantity. yes sir. Its You can tell me about the dimensional formula in the comment section. I will tell you. what is the mlta form will be? Tell us in the comment section. Look at its look at the archery friend three three three arrows one Driving along. so work done on time It will be more. It will be more. Look at me friend The example of Bahubali was written for this reason Rate of work done Work done divided by time. Average Instantaneous. Now a question Look NEET 2023 asked questions like: A particle moves with the velocity So much. This is the equation of velocity. Horizontal under the extent of force. These Also give us the value of the force in question It has been kept. What will be the instantaneous power? Now you have grown a bit, so a little bigger Questions are asked. Instantaneous How much will the power be? don't get confused look In this that now those simple ones Question. Ask a little bit bigger questions If you go, you will be asked a question in vector form you know the value of force velocity you know the dot between the two The product that is instantaneous power hum sir force value sar 10i cap + 10j cap + 20k cap dot a this will come 5i cap is plus minus 3j Cap plus 6k caps. Hmm. OK sir. Now Look, let's simplify this. So, 10 more It will become 5. i with i, j with j With this, it will become -30. 20, 6 * 2. This bun It will go to 120. 120. This will take away 50. 20 Saved. 140 votes will be the correct answer. The exact one. Which one is given in the options? 140. D option will be created. is this the correct answer Is? Take a look, check it. D for or right The answer is 140 volts. Now, it has small There are also questions that look in a way I had written about power, average power is Equal to work done divided by time. so this Work done, work done is equal to change in There is also kinetic energy. for the umpteenth time Work done is equal to we will also write mgh. Will also write mgh. So see different-different We will use this form for this type of situation I will apply. So once you have what we have Checking the questions whether they are There are conditions. this was a good question In vector form. Now such questions kinetic energy can come in small is there any information about or mg The information had been given and it should have been given. So in that story we will put mgh here or we will put change in kinetic energy and We will divide it by time. perfect this power It was the story of. The collision is now beginning Story. Collision means clash between two bodies or occurring between more than two bodies clash and in that clash there were incidents of very terrible level Forces are generated, experiences are If so, it is called collision. Example As a car accident. if I put this bottle to my forehead In a way, it was a collision. But I've Hit me gently. if on a larger level this is producing energy. Impulsive If it is producing force then it is good This will be called an example of a special collision. As When you play cricket, the ball hits the bat When it touches I feel such a shock. If So that is an example of a collision in a way Happened. So collision is in the life around us Look everywhere, there is a collision in our house every day It happens sir. hey i am not talking about collision I do it. Ok. First I'll say something Am. I fight with my sister. After that sir mummy or papa comes and When you do my laundry then there is a conflict between us In Collision. It keeps happening in our house yes sir. First I would talk between me and my sister There is a collision in. then me and my mother There is collision in between. Yes. then i I get everything collated. So this topic So mine is lying there sir. you can move Forward. I am leaving from here. That was a matter of collision. of physical collision We will talk about the conflict between human emotions not in between but physical between two bodies It is happening in a form. so collision it is the Event. It is an event. you know which Impulsive forces are acting between a two or bore bodies for a short time which result The change in this linear momentum is very This conflict is happening at a terrible level and there This change in them brings a change in their momentum is there a change in momentum what is the change in Momentum then impulsive very large amount Pay forces are produced, see here Friend, it is broken, it is broken, it is broken brother How big is the iron that it breaks Is. That means it was made of Tata Steel but Still, damage is occurring. so that means What an impulsive impulse must have been created. What a shock that must have been. so by the way The collision is read. because of which here Momentum is linear momentum change. So Effect of non impulsive force like a Gravity is not taken into account. These Why did you ignore me brother? because look we read that gravitational force is the Weakest Force. The weakest force. And Impulsive we say that of large amount Force for a short time interval. So when we If we talk about collision then it will happen in a very short time we will talk about period and there high The force with magnitude will be applied, right? Of high magnitude. so over there You can't neglect the effect of gravity You can do it and go. So look at this impulsive Force will be applied between the two. He is one It will fall on someone else. like this car Here is the impulsive force and the reason for this car Impulsive force from here on out. Although J also I can write if I want. take it and do it I gave it. Impulsive force j or I It is represented. So this is also a Applying in opposite direction above the system There are forces. yes sir. although normal It is the force which is the impulsive force Does role play. But this force is internal It has happened, right? If I did this whole thing as a system I accepted it then. Gravity was felt earlier, It was felt even later. can make a case like that yes. and gravity is negligible here Will go into comparison of these. so in short this There were internal forces and we called gravity I told you the reason why I neglected. So there is no external force here. Is. So any type of collision It will be as per our syllabus Linear momentum will be conserved sir. so which I had studied PCLM in my childhood PCLM will be used. where did you study PCLM Was? Now in Chapter Number Four Laws of Motion Had read. Read it in Laws of Motion. His A little experiment is going to be done here. If No, if you remember then revise it a little Take it son. There is nothing big in that. There is still a little myth that it is not so for a collision to occur between two bodies It is important to always be in contact. here at So I am coming. I am coming here. But Sometimes even without touching, just by talking Collision may occur. It was a joke. But when we study at the atomic level then it is as if one electron is pointing to another When the electron comes near it then it reaches very high speed Both of them were coming towards each other from one side But as they get closer Ram Ram yes as he comes closer will go the way the repulsive between them If the force keeps increasing then at some point you will come closer The instantaneous velocity of both became zero Then they started running away and then in between the two There was no collision but the concept of collision You can apply. So that means that This is a collision incident. So it is not necessary That both will definitely come in contact. Talk, you can fight by talking From a distance. So what is may and may not be Physical contact. It's a small thing but You have to remember this as this is one of the MCQs This was asked in NEET once. So our It may also come in the examination. Ok? Story ahead. Time Interval Considered Very Small Due to the impulsive nature of force. We a lot For small time interval we use collision We are going to apply the concept. just before The Collision Just After The Collision. just before the collision this velocity was just after the The collision occurred at this velocity. of the same situation For this we are applying these formulas. The collision happened after half an hour. take this one And he went away. He took him away. all matter We will not discuss if there is a solution Of collision. Ok? so just after the We discuss the collision just before the collision are going to do it. Now this collision can be divided into two ways It is classified. a based on Direction second based on kinetic energy Conservation. What is in the direction? That Headache from forehead to forehead. Look, these balls are facing each other were coming towards. First look at this red one The velocity will be higher. then go to this blue Had a confrontation with Wale. So, a collision would occur After that the red velocity has reduced a bit It must have happened and this blue one ran away. So Look at the velocity of both of them here and the direction of velocity and the collision direction of collision Direction means just before the collision and just after the collision if you see Velocities here along the same line Are. Hum sir so this is a head on collision An example took place. On the basis of direction we Let us define it. First classification. Second Oblique. look at it before the collision Velocity The velocity of the first ball is I was in direction. After the collision, its The direction of velocity changed. Here But there has been a clash. this collision has happened this Between the surface and the wall. so after the collision The direction of velocity has changed. So This story will be called Oblique Collision. what son? known as oblique collision Is. One thing ahead classified in another way We do. See, these are examples. Yes, Understand. This is a very nice diagram. Someone please say one thing. As high as any one ball hit the height from which he fell was the same Back to the heights. what is the meaning of this It happens? What is its meaning? That where the collision occurred when at the same instant The collision must have occurred with a velocity That much velocity he gained back It will be. even a little bit here There would be no energy loss. as much as initial energy equal to the initial kinetic energy That collision happened to be the final energy collision Even after that he has the same kinetic energy He had energy only then he reached that height Have got. h height came down h height went up Is. This means that the collision that happened here The incident happened here between the surface and the ball A collision occurred in. anywhere in this There is no loss of energy. So Initial Kinetic Energy Equal to Final Final Kinetic Energy. anybody here Any loss of kinetic energy Has not happened. Delta K Change in Kinetic Energy Zero. As much as it was initially It will be in the finals. Perfectly Elastic This will be called an example of collision. Or called an example of elastic collision Will go. The second one is as inelastic as my brother It fell from a height, exactly to that height No, but I could reach a little. Little reach Found. It was able to reach h1. so as much as It must have fallen down with a velocity that was not that much It might just be a little less than that. a little more than that C may be less, this is coming up Velocity. So v is smaller than u here Initial Final Final Kinetic Energy is That will be less in comparison to the initial. So Change in kinetic energy not equal to Zero. Meaning there is some energy loss here It must have happened. In this event, the kinetic energy is There is a loss. OK sir. and perfectly The inelastic collision fell from above No, I will push it back. So when there is a collision After that there is a collision between the two they stick to each other there But maximum kinetic energy loss occurs Is. Delta K will be maximum. here at The loss of kinetic energy is maximum. Here the initial kinetic energy will be That would be too much as compared to the final. Understand that these two will stick together. So Both in a perfectly inelastic collision Will stick. Just understand it like this. Two bodies It will stick to it after the collision. if it will work then It will either stick to it or it will not move at all. As such Understand it. These are perfectly in elastic This is an example of collision. where the energy Maximum loss occurs. any bit in one No. There will be a little loss in one. in one Maximum loss can occur. There should be maximum loss Can. Means the energy is much higher than this There is energy loss. We call it perfectly It is called inelastic collision. these classifieds How to do it. Now let’s read in detail Each one of them. first inelastic then first Elastic then inelastic then perfectly Inelastic. To see and understand. what momentum Is conservation for everyone? Yes sir. So first write one point here that Sir Momentum for this type of collision It remains conserved. and sir anybody here No waste of any energy It happens. not speaking of any kind Needed but there is no loss of kinetic energy It happens. Kinetic energy conserved. Meaning It tells you how it will be written Am. It's same to same point. turn around Let us write that force is involved in this During this collision is conservative. This too We know. yes sir. then only linear We had applied momentum conservation. OK sir. The Mechanical Energy Is Not Converted into heat, light and sound. Now Energy is not being wasted anywhere. then So we applied energy conservation. So there is no dissipative energy here. will go. Meaning no dissipation of energy will be. Now those who remember its examples Are. such as collision between sub atoms Particle. between subatomic particles The collision that occurs is called elastic Let us consider the collision. Collision Between a glass balls. this glass ball one So you must have seen it and read it. Oho If you haven't read it, you must have played marbles I have not understood the game. in between the glass-glass The collision that occurs is perfectly elastic Type of collision. Shoot a bullet like this. They By attacking with that it would hit the other bullet. The second bullet is on rest, then after that The second bullet starts to move a bit and with the first means like colloid The first one came to rest first and then the second one This marbles guy went into some motion Please tell me if you have played the game or not I will tell you more about it in the comment box I will tell you stories but first tell me these marbles have you played this game or not then there But the collision that happens is perfect The other is elastic type of collagen How to have a perfectly inelastic collision of numbers I am telling you about what will be written. See There is a little kinetic energy loss here. it occurs. yes kinetic energy here There is a little loss. What Do you have any characteristics sir? Momentum is every Some people have it conserved. So the point You keep writing. If someone asks me separately Then keep writing the point that momentum is conserved It happens. Whatever forces we have taken here Yes, he is a conservative type, sir. But there is something non-conservative here There will also be types of forces. because of which Energy Conserved Kinetic Energy Conserved She will not stay. Isn't it? Total Energy: Anyone ask? Let us tell you that the whole energy of the world is conserved does she live there? yes sir. That conserve energy It remains. because some part of the energy is It might have been converted into heat or sound It must have been converted into energy. the energy that is in reality The collisions that occur are so inelastic They are of the same type. Whenever you see a collision It will happen, a sound will come. Some heat will be generated. This way These are the collisions we have seen around us. So in reality this collision is is in. So collision between two vehicles. These Look, I have given the example of S. then collision Between a ball and the floor. right now which The majority had given examples It was a part. Before we understand the ideal case Was studying. This is considered an ideal case Is. Then there is the perfectly inelastic collision He came and fixed it. It's over sir, it's over. So this story For this sir we can conserve the momentum Are. You can apply for PCLM. There are no restrictions for PCLM. But there will be maximum loss of energy here. So if two bodies stick together, after collision Afterwards both the bodies got stuck to each other will go. After that both the bodies are somewhat same Will run away with velocity. that story we The Story of a Perfectly Inelastic Collision They say. The energy here is kinetic energy. maximum of , maximum of kinetic energy There is a loss. Ok? Now look at the reality This mug mug throne on a wall and a stick meaning Understand such a bullet from a gun that Whatever you stick on the wall, it sticks. So there will be examples of this. After that Meaning they fire bullets at every jump. This bullet example is more relatable Is. We fired the bullet close and in front of the one It got stuck to the body of the person in front. that brother He also got stuck himself. So both the bodies will move now So, it will either go together or it will not go at all. So after the collision that bullet and brother Both will either go together or they won't go at all Or brother will just leave. so there both They stuck with each other. So Collision after that if two bodies get stuck then that story We call that collision perfectly inelastic This type of collision is called. So these three Understand the collision carefully first, son. Then We will come to more questions about this. Look Hey son, there is a small derivation. small one so it's not but it's a little bit bigger but It is given in NCERT. So we give him a Bar derivatives. Then I will tell you that I will teach you how to do conceptual questions are solved. Understanding the First Derivation what is the point that a sphere came some u1 collides with another sphere with speed u2 He was running with speed. obviously colliding Is. So this means u1 will be greater only if I am able to reach it out. then it collided I am getting it. Ok sir. Perfectly Inelastic collision is occurring. Perfectly Elastic collision is occurring. and to collide After that the velocity of the first ball becomes v1 someone else is getting it v2 just after the This was the story of the collision. So sir two stories we You can apply. Perfectly Elastic If there is a collision of this type then the kinetic energy There will also be conservation and if there is any collision Momentum conservation will definitely happen. So first pclm according to we momentum Let's do conservation. look carefully This is a derivation. Keep understanding together. So first I can write m1 u1 carefully keep understanding keep writing along with me It's just a small derivation. For this derivation After that, everything is easy. just a little A derivation. Even if I don't make this derivation Even if I get it done you will understand everything. But it is given in NCERT. So son It is our duty to do the derivation once Take it. Let's do it quickly. then the other one Look at the velocity. m1 v1 + m2v2 sub rightward Only positive will be written in the direction. Let us take the one from One One aside. two to two Let us take that one aside. So m1 u1 - It will become v1. if it comes this way then the other on the other side it will become m2v2 - u2. this one is m2 u2 The term will go the other way. so this There is equation one. for the same condition means that for this incident, for this incident just before the collision just after the collision You did momentum conservation just like that Conserve energy. Kinetic energy. We have already read it earlier, not perfectly for elastic collision or elastic conserve kinetic energy for collision It remains. This means that k initial = k Final. We are going to apply this event back. have been. As an example, first What was the initial energy? 1/2 m1 u1² + 1/2 m2 u2 = 1/2 m²v1² + 1/2 m2 u v2 1 one on one side to to Put that one aside. so 1/2 1/2 so although all He will die first. Then m1 u1² - this second term will become v1² Everyone's one will come towards one 1 1/2 1/2 get cut Will go. m2 look carefully brothers and sisters this v2 squared minus the square of v2 The one with u2 will come this side so the square of u2 will now a² - b² Do you remember what you used to read in your childhood? were a² - b² = a + b and a - b we read sir These are the things that have happened. So, m1 u1 - v1 and u1 + v1. same thing here as well m2 Look carefully, son. v2 - u2 and this is will go to v2 + u2. This equation is called equation Give me number two. This equation is called equation I have said number two. Ok? Now these two Let's use the equation. of both of these Let's take the ratio. Equation one is something like this. m1 u1 - v1 = m2 v2 - u2 Equation to m1 u1 - v1 u1 + v1 = m2 v2 - u2 and v2 + u2 in Let's take the ratio of both. Understanding Equations 1/ Equation Two. take the ratio of these two But what will I understand sir? that m1 m1 die Will go. m2 m2 will die u1 v1 would kill like this yes u1 - u1 u1 - v1 and v2 - u2 these are dead will it be saved sir will it be saved u1 + v1 = v2 + u2 yes sir we got this formula now pay attention from here I make the equation for v2 From here the equation of v2 will become u1 sir + v1 + no means u1 will come this way then If it becomes minus then it will become -u2. this one Whose equation was formed? of v2. what to this I mean, where did you get this from? what happiness Did you find it? what joy did it give you Sir? Tell me this. Did you find happiness? Happiness is just This is how I got the equation for v2 Is. Did you find it? got the equation of v2 is in the form of u1 u2 and v1. So from this What was the benefit sir? what we just wrote Conservation of Momentum I am here here The formula in place of V2 is He has just driven us, he is going to write I have been. I have given the formula of this V2 here I am going to apply. As soon as I do this I am applying the formula V2. V2 Equal to see like this it was like this U1 then what did you come sir? U1 + V1 + V1 and - U2 as I will apply this formula, simplify it I will try to find the value I will do it. because in the whole equation now There is only v1 which is a variable. There is only v1 in all equations which will be the variable. and this v1's If you make an equation, you will get an equation like this It will be. We will get such equations that v1 = m1 - m2 / m1 + m2 * u1 * u1 plus If 2m2 is one then divide 2m2 by m1 + m2 into u2 look carefully see the forest, first the forest okay two so the first two one ok sir second That means its second part will be written as v1 So first u1 then u2 v2 is written then u2 then u1 Okay then see if it is one then 1 - 2 if it is two then 2 - 1 below then only m1 + m2 is coming in everything We are sir. Ok. There is a forest here and there are other ones of two times. here there is two so the second Wala means it will become one. His two times. This is the way of writing. do it two to three times If you write it, it will be remembered automatically. Bus Write it down yourself two or three times. These It will be remembered automatically. This is the equation of This will be beneficial, son. The advantage of this equation What will happen to you son? straight to you Satak. Would this colour be better? No, not at all. Ok. which colour Would this be better? No sir. Hmmm.. just one last time, yes, if that's right If it is not there then it does not matter. Whatever it is write I will take it. Ok. I'm liking it. It will be good if It looks good but we like black color. Ok? We gave it a black vessel and Inside. We painted this and the inside also black Is. So in short this is the equation we are getting What is the benefit of that? The advantage of this is that it is happening that we have to do it for collisions The final speed is being achieved for one and that for two I am getting it directly. get that direct It is going with this equation. any headband No. No forehead band. Just Equations I mean the first one is of 5 kg. different one It weighs 10 kg. Give initial initial speed 10 It has been kept. Its speed is given as five. Tell What is the value of v1? tell me just after the What is the value of Collision v2? straight to this flower We will get benefit from it. So this is NCERT I had given this derivation. because of this I told you I will solve the questions using this derivation I will not get it done. I mean talk to me Why shouldn’t I get it done? because even more than We have an easy trick and that is NCERT I have mentioned it but I am not using it I haven't done it. So why don’t we use it What should I do, son? If it is mentioned in NCERT then we You can use it. as he said Coefficient means this trick, whatever method it was I told you. How can it be used Is. I told him lightly. Now I If you have any collision question I teach the basic concepts. Basic There are concepts. Firstly apply for PCLM Can do it. The second is energy conservation You can take help. Ok? So this is just And only for the perfectly elastic collision Was it applicable for that? Yes. Our Syllabus Most Perfectly Elastic Collision in Or it is a perfectly inelastic collision. Two These are mostly the cases. But I want to That any question may come before you. You should get the concept. Learn to catch the roots Needed Are we okay? so its formula is Based questions will be made very directly. V1 If you ask me to remove V2. otherwise somewhere But if this incident does not happen then you will be in trouble. So I am going to tell you a good incident which is mentioned in NCERT. There is a mention and I teach how to use it. one thing to look at is a term coefficient of Restitution. who says what that initial is the relative velocity just before the Collision is its initial relative speed. It is written as velocity of separation. Velocity of separation i.e. v1 u1 - u2 Velocity of separation means U1 - U2. U1- U2 means to reach out the relative velocity is that just before the The relative velocity in a collision That is called velocity of separation. And Sir it is written U1 - U2 because U1 Only when she grows up will she be able to reach others. Both collisions occurred. Both of them supported each other Apply normal force upwards. Impulsive feeling happened. At that time the velocity of both is same May have been. then after that the velocity of both Some things became different. V1 V2 what we just did I had taken it out from the flower. Ok sir. this this incident Hui. Look carefully, look carefully. Look carefully. not separation from the previous one is called approach. The U1 came from Speed. U2 Collided with the shell with speed. at a Time collision deformation occurred. after this Both the balls are running at different speeds They are engaged. Ok sir. now just before the The relative velocity of the collision is, That is called velocity of approach. Velocity of approach. means to each other to approach to collide with a the velocity that would be needed to get to the other It is known by its velocity of approach. And here it is going away, now there is a collision You both are running away from here But if separation is taking place then the velocity of Separation is said to happen just after the collision. So in a way this is relative velocity. But for Just After the Collision It is called velocity of separation. and just We speak before the collision Velocity of approach. So look at approach U1 will be more, U2 will be less. only then this reach He is able to get it out. then U1 - U2 in the second case After hitting the separation for V2 If there is more, it will run faster. V1 He will follow behind him. then it will be written V2 - V1. So this velocity of separation and The ratio of velocity of approach is called It is called the coefficient of restitution. This separation is what reformation is all about It represents. While the approach is Represents deformation. So The basic definition is done first or somewhere it is said that just mean it is the ratio of impulsive Refashion. Representing the Reformation Separation He does. Represents the deformation approach He does. So we can call their ratio as coefficient. It is called of restitution. Now its value It is between zero to one. Remember the value of e can be either zero is or can be greater than zero but is one Or it will be smaller than one. Exactly E = 1 Is. This means perfectly elastic Collision. No energy will be wasted. Kinetic energy will not be wasted. It will remain conserved. e = 0 maximum Deformation Maximum Deformation Both If we walk together then that incident will happen. So Let me remind you of one thing Sir that is a perfectly elastic collision so The coefficient of restitution becomes one. there is a perfectly inelastic collision The coefficient of restitution becomes Zero. Remember this, son. Remember this, son. And this incident is bigger than zero and bigger than one Small E is the coefficient of restitution It will get value. it is never negative will be. It will not be negative. look carefully These are small things. Now question this I will get this coefficient of rate calculated How to find the value. so it is the same incident Look, you have two balls, come near you have been. Never get stuck on the flower. I I am not even suggesting that you should buy Phula I have to memorize it. U1 - U2 no. what have i said that the relative velocity before collision i.e. velocity of approach after collision The relative velocity of Separation. Ok? And the ratio of these two is Coefficient of restitution. So there’s a story in which two balls come close to each other have been. One is coming from 5, one from 10 It is coming. and this just before the collision The Collision JBC and this just after the Collision J.A.C. We have been asked what is the coefficient of What will be the restitution? Here you go. asked this Is. So what is e equal to? Velocity of separation divided by velocity of Approach. We are talking about Sir Sir Separation i.e. its The relative velocity of the latter. Yes. So here it is The relative velocity will be the velocity of It will be written in the form of separation. so four mine both in the same direction 4 - 3 so This will become 1 meter per second. OK sir. And Joe Relative to Just Before the Collision Velocity is the velocity of approach It is known from. both looking at each other If you are coming in direction then relative The summation of both will become velocity positive That means 5 + 10 will become 15 meters Seconds. So you can write it down very comfortably. write in very leisurely and beautiful letters You can sir. it is a 1 / 15 this will happen Coefficient of restitution. don't confuse Creating a result that always returns e = u1 - u2 and v1 v2 - v1 means any such formula don't memorize it, i wrote it upside down but There is no need to memorize any such formula. Velocity of separation divided by velocity of approach. This should be in your heart. These It is also like Brahmastra. Because e = I am writing it again and again so that it stays in your mind Let this matter settle down. If e = 0 then Perfectly Perfectly Perfectly inelastic collision in elastic collision then if e = 1 then e is exactly Elastic Collision is Elastic Collision Will go. and if e = 0 to one So inelastic collision means inelastic We gave an example of collision. this work This is the story of. From here you can see how you dance There are a lot of questions. Dhoom Dhadak There will be questions. see we just need a collision Only two concepts should come for this. that's enough Will go. One coefficient of two concepts The one for breast is Law and the other is PCLM. Memory one for collision two for collision It is important to understand the concept. A PCLM And secondly this is the coefficient of restitution. With this all your questions will be solved. Velocity of separation divided by velocity of approach. From these two stories, all your Questions will be created. son all the questions It will be done. Watch it carefully. Now I see Let me tell you different cases of this. You will enjoy it. You will enjoy it. I swear on my mother I am speaking. You will enjoy it. see its Derivations are given from that flower. right now which I told you a scary formula Let us get the derivation done from it. But I'll let you See, I will give you the feel of it by using it. In the example, elastic collision is occurring. Head all collision means head colliding with head Is. The mass of both is same. and has given The condition is that e = 1. means perfectly Elastic Collision. Perfectly Elastic Collision means e = 1. Great sir. So What is the event here? that sir velocity of Separation Divide by Velocity of Approach V can write it a v1 v1 - v2 we sir divide I am u1 - u2 Yes sir this is also correct. e = 1. Yes, there is one. so this v1 - v2 divided by u1 will give It was written upside down like this. The formula we learned according to that v2 - v1 / u1 - u2 that is It will become equal to 1. Yes sir. So this u1 - u2 = is written as v2 - v1 This is the first Equation I. In our opinion, a first The equation has come. OK sir. Although these There is an equation, look at the kinetic energy Initial Equation to Kinetic Energy Final and derived the same equation Is. Secondly, this is the first law that we told you Firstly, this has to be applied. 2nd PCLM Have to apply. Second PCLM Apply Have to do it. So Sir PCLM says that P initial = P final . initial m1v1 initial m1u1 + m2u2 = m1v1 + m2u2 Now you know that this story We have already assumed that everyone's Mass is equal to equal. so why not this month should be cut off beforehand. why not this month should be cut off beforehand. Because the mass is m1 = m2 We are assuming in the story that There is a special case. Special case sir good. So the equation we get is like this u1 + u2 = v1 + v2 This is equation one. This is equation one. If you have to solve these two problems then solve both of them once If you do summation then get these two united So what do you get if you do v1 1 + 2 will u2 u2 will die v1 v1 will die then This becomes 2 times u1 = 2 times v2. We ok this means v2 will be equal to u1 And if you do it with the same approach then v1 Meaning, what will you do with both by putting a minus sign? If you subtract then v1 will become equal to u2 hey ok sir what are you confusing what is this v1 v2 tell me it is straight talk no Nonsense this means that after the collision What is Velocity v2 after collisions The initial velocity obtained first the initial velocity of the first one That means it moves at 10 meters per second. Had been. So this is now 10 meters per second It has started moving. And sir the second one i.e. this v1 v1 = u2 came. This means, Sir, that If the person was walking at a distance of 5 meters sec then after this the velocity v1 = u2 It becomes equal and u2 = 5 meters per second. Meaning both of them exchanged velocity. Yes. Special Case Number One Elastic collision mass equal at that time they exchange Their velocity. See if any one of these people It is coming at 10 meters per second and this is 5 Going by seconds on the meter. between the two I might have collided. Now this one will start running away from five And it will start running from 10. Opposite Opposite The respectful direction that might be coming Regarding. What an amazing property you have got. It is derived from a formula. But I told you PCLM and Take the coefficient of restitution and With his help I have driven and told you Gave. Look at this carefully. Anywhere If you have any doubts, ask in the comment section Take. Otherwise I am there. any how Should you ask me, son? So take a good look at it Once. There is no confusion, right? clear These are cut things. Are you understanding things? Ok sir. Look now its another case yes. Its special case number two that if if A ball collides with a wall with speed u This is the story from Just Before the Collision. This is the story Just Before the Collision. Just Before the Collision You hit speed. Now V This ball is going back up with speed. So This is just after the story. just after the This is the story of a collision. just before the Collision. The wall was at rest. coefficient of The restitution is between the two. It is E. It depends on the property. E Depends It will depend on the nature of both. Head banged V Ran at top speed. Sir this is initially Was on rest. Finally she was also on rest. So Here, the velocity of approach is U. Will go. And let the velocity of separation be V Will go. So the law of coefficient of breast is something like It will be written like this. The velocity of separation will come Divide by velocity of approach = v / u. so that's why you will find v = u eu That means if it collides with u then v = e will jump above u. above how much Will it jump? Will jump above the EU. what a cute The case has come before you. a little bit of it The question can be formulated like this. Such as no wall tuck tuck tuck ting ding ding ding ding ding ding ding ding look carefully yes a ball which came at 5 meters per second from and sir here the coefficient of restitution I have given 1/2. so this sphere just before the Collision hit five. and just after the collision after collision after collision this How high will it jump? After collision, its Velocity will become E * u which is the value of E is 1/2 and the value of V is the value of u is Five is 5/2 meters per second above It will jump. What an amazing thing sir? What does it have an application? So any stationery that It will be a very big mass. There will be heavier mass on it If lighter bodies collide then E * U This will become the velocity of the lighter body. Ok? This was an example of head-on collision. If you want then it has collision collision oblique You may also like this one. what do you like mean If any question comes then you can ask it that this is the wall that came down from u. to collide with Look later, its direction has changed. We Sir the direction has changed. Meaning of Oblique There has been a case of collision. Look carefully. In this the change in the story is that where But whatever is normal then Its speed changes accordingly. Otherwise there is no speed change. see ux is ux but the ones who are normal It was agreed upon. This became normal. These It became normal. So normal is in between the two It will be normal. That's an impulsive thing, right? So The direction of this impulsive force Accordingly this velocity will change. Such as Let's assume this is uy. So here the The velocity i would be vy = e * uy It will be. What an amazing thing Sir? what an amazing talk? Make it a star. This is due to oblique collision A case will be filed. vy = e * uy written as e * uy Will go. See ux I took its component. it's ux. There is no change in ux. Just After the collision. this is just before the collision Story of. Just after the collision. Just The Story Before the Collision. looking carefully Take it. From special cases to more useful cases There are plenty of such small questions from You will find it in books. abundant In quantity. will you solve any good book So. But grasp the concept, son. yes, no that you should run after the formula given by NCERT I have given it in. Good for derivation. Sometimes it also comes in handy. we believe The fact that many cases are very easy to solve with that formula They can also be derived easily. To understand They also come. But such a big formula How should I remember you brother? and by the way so many When the chapters are put together, which ones Will you remember the formulas, son? Yes. So Grab the concept. Velocity of approach. Velocity of separation divided by velocity of approach is equal to the coefficient of Restitution E. The value of e is zero i.e. inelastic collision perfectly The value of inelastic collision e is one, i.e. Perfectly elastic collision. OK sir. Now his opposite case is case number three that now The wall is moving a stationary lighter towards the object. Its mass is very small Is. The mass of the wall is terrible. Sir If the wall is coming towards it with speed u, then the velocity of approach will be written as u - 0 That means velocity of approach will be written as U And what will be the velocity of separation written as Sir? Look carefully. so say just after the He might have started running at some speed in the collision. Now we don't know some speeds. That is it Have to take it out. This in Just After the Collision Son, he must have started running with some speed. so he We just have to maintain the speed. Ok? and this What is the speed of the wall after collision? Will there be any change in No. heavy filled fierce Is. So what about its speed? The speed of the wall reduces a little after colliding with it will go. There will be some slight change. He counted it It will not even go that far. So sir this The velocity of separation is written as v - u. We Sir, you told me this thing practically. Ok. after hitting the wall like before So she was on rest. nobody in the wall There weren't many changes. Same beans There is a case. So the coefficient of restitution is According to this, E is equal to the velocity of Separation Divide by Velocity of Approach. OK sir. So we know the value of E. I don't know about the story sir. velocity of Separation V - U divided by will come U sir. The EU will come out on top here. These are v–u and you will get velocity u + e u means like this can also be written u 1 + e means whatever you you want to write but do not derive equations like this Such equations will be made if there is a perfectly elastic collision if I write, see this story told here Here, let me tell you this thing that if else if If the perfectly elastic collision is e = 1 then it is How will the equation become So pay attention to how this equation will look like Look velocity = u + 1 * u so this is 2u That means if this is a perfectly elastic collision If the value of e is one, then if it is greater than 10 He will run away. The wall must be coming from 10. Wall 10 If this ball is going from then after collision will run away from 20. 2u means 20 meters per second Will run away from. This is also a good trick. Look carefully. But this is a special case It will become a special case. Look at the special case What is a special case? Special of Special Case case if is written as a = 1 then you can say that it will run from 2u. this velocity call How much will it be? It will become 2u. it is coming It is a clear cut matter, isn't it son? upset about it It is not happening, tell me many cases Given. No no no no son. two three Only four cases have been reported. These flowers actually bloomed They are informed by. But I don't want to yes, tell that to Phule. Ok. Now number four The case which is most imp. the first one the most More imps. The fourth one is even more IMP. that if two bodies are going and Perfectly inelastic in between There was a collision. Now inelastic means e = 0 and e = 0 mean velocity of separation Divide by velocity of approach = 0. so this When will it be zero? When there is a conflict between the two The relative velocity after that, that is The velocity of separation should become zero. Separation It should become zero. That means this is V1 - V2 or V2 - V1 V2 - V1 this should become zero. This means that This is V2 and equal to V1, yes sir. both sticks Along with that, let's go for some V Days from Velocity. Both of them will go together for some V days From Velocity. What an amazing thing, son. So We have to find this velocity. What Do you want to take it out? We have to find out this velocity What will be the value of VDS? very famous It is a ques. This is a very famous case, son. These Questions may arise. either ask for derivation Will you take it or will you ask me directly, son? With its formula in numericals. So there is nothing new in this. Write straight Initial momentum. because kinetic energy There is no conservation here. But PCLM is You can apply, right? Momentum is It is conserved. Hmm. sir ji initial initial Its velocity in m1 is u1 and m2 that u2 are finally moving in together By combining m1 + m2 into common velocity v Common velocity is taken out v d = m1 + m1u1 + m2u2 divided by m1 + m2 what is amazing The formula is coming to us and this Very cute based on formula Questions are asked. take this special All four cases are mine, four each. They I have told you about four cases. Four cases I told you which were my favourites. Ok? These are not favorites, they are asked. Very Its bases are asked very frequently Pay question. Now look at the series of questions let start. I am going to ask five questions have been. Ok? Five on Collisions Question. Great question. Conceptual Question. The first question is about your eyes It is visible in front. which is a kind of revision It will go away. what are those two blocks near you. Ok? Two balls, this one. Correct Is? bearing of a mass each moving in Opposite direction. Ok? that's velocity is given as a v speed is given v. Colloid Head There is a head on collision happening. Predict outcome of this collision assuming there is a Perfectly elastic collision. Perfectly There is elastic collision. It is a matter of e = two to one. Ok? And a head on collision is happening. Both The mass of is equal. What will happen? Both the velocity will be exchanged. so straight The answer to the NCERT questions will come soon that they reverse the direction of a motion and will run at the same speed because both the speeds That's why I had given the same thing to him. Second The question is before you that a bob a The pendulum is released from a 30° or 30° angle It is being released. So as soon as this There is a block named A. Bob is here, he'll come down So it must have gained some speed. Value So this is the speed V. OK sir. Now it happened That vertical hits another bob B. These small means its mass is m and these are the neighbouring ones Hitting a bob. A Bob with a Pass b whose mass is m whose mass is also m It is just that. He is heating it. Ok? And It is mentioned in the story that same mass rest is on Is. It was initially on rest. this just There was a story called Before the Collision. just before the Collision. This was the story. Just Before the collision. OK sir. how high does the bob A Rise After the Collision? This is the one that How much will the return rise after the collision? yes Maybe after this, this yellow one He should get some velocity and he's gonna He has some in the opposite direction velocity should come or it should come in the same direction Some velocity but it should reduce. may it be so Can it be? Yes Sir, it can happen. These This is the story of Just After the Collision. Just This is the story of After the Collision. But one thing He told that whatever collision is there here It is elastic. Elastic means E = For 1 and E = 1 it was stated that if both has same mass, then it changes its velocity Let's do the exchange. means initially this The yellow one was on rest. so, finally Finally it will come to rest. just after the After collision it will come to rest. This Previous Bob A's Situation B's Situation will become like A and situation of B will become like A The situation will become like this. We sir are now A V collided with velocity because from top to bottom There must have been some velocity. that velocity Now to whom will you give it completely? To the one with B He will give it and the one A will come to rest himself. Sir when did the concept of velocity exchange come into existence? is it applied? when elastic collision And the meat of both is same. What both Is the condition satisfied here? Yes. Then it is applicable. Otherwise it is not so. So Sir is sitting in this story. So we have I applied for it. It made our minds go crazy. Just before the collision Just after the collision. This will come to rest. Then it will not jump at all. Height of what? rise of what? so write it straight in letters that bob a does not rise at all After the collision. He will come on rest. Its velocity has been exchanged. What Wonderful question. another one did you see this have you done an experiment in which one Catch and release one. second from the front One will come out from the side. hold two release two do it. Two will come out from the front. three catch three Release the . Three from the front. three such Will oscillate. Four is four. saw this story have you? Have you seen it? If you haven't seen it then your You can do these experiments in the lab will go. The basic reason behind this What happens is the conservation of momentum. and conservation of energy. It is here isn't it Elastic collision occurs. What happens? Elastic Collision. Meaning, one with one, Two is with two, three is with three. Look So it is the same thing here We are having ball one sir. He is going at some speed V Used to be. Two and three nearby. two and three like this The balls are lying there. so the best one out of these Which would be the suitable diagram? this to us has been asked. We have been asked this. So Here first let's check which type it is It is the nature of. Everyone's mass is given as mm. But What type of nature is the collision? So Sir ji if the collision is elastic. read straight So collision is elastic. Collision Elastic is provided. So you know what happens Is? First there will be a collision between one and two. There will be a collision between one and two. So one V Coming from Velocity. He is on rest. Ok sir. This is just before the collision. Just What will happen after the collision sir? Just after the collision one will come to rest and two He will run at some v speed. This is the first This incident is a matter of first collision. just after the Collision is first and foremost a matter of collision. Now watch The one at rest. to gonna do something v It's from Velocity. see after collision Velocity is being exchanged. Why? Because this is a perfectly elastic collision. Because of this, see what will happen now? The Third One I was on rest. OK sir. so just after the Collision one two came to rest and the third one Some will start running at V speed. yes sir this is just after the collision why this Has it happened? This is velocity exchange Collision One. This is collision two. between whom Was this me? Between one and two. this two There was a collision between end and three. Sir this Velocity is exchanging. Why? Because sir its velocity is same as its mass bean is bean and elastic collagen This is an example. then return both conditions I was feeling satisfied because of this. because of this This incident happened that sir is the best from here Possible diagram A will appear. Best Possible Diagram A will appear. Now, I will address this question Let me mould it a little. mold it a bit Should I give it to you or tell me, son? Look, your answer has come. This is your answer that Answer with B will be the most accurate. where is this from did I do it? 1/2 from where? This happened na v. Look, this is the third one. he is running away from v Is. So this answer with B will be correct. But I am asking you, son, I modified the equation so that e = not 0 if e = 0 a = 1 if e = if It is zero. e = 0. Perfectly Inelastic Is. Perfectly. is inelastic. The value of e is zero. So which one of these Hey Ram Ram Ram Ram, it's okay. pardon of these Do it son. It is getting very cold. So Which of these options is more correct will it remain? There is a perfectly inelastic collision. So which would be the right option? A, B, C, D. Meaning 1 2 3 A B C. I have the answer to this Tell us in the comment section. If all three Tell me what the story would be for all three. Ok? So, in the story so far, you have I read Perfectly Elastic. Now perfectly Let me start with inelastic. see here It has started from . and perfectly inelastic What happens is that we walk clinging to each other. what happens sir? Let's walk clinging to each other. As that this was the case. This was the case. will stick to it and velocity will be written as m1 + m2u2 divided by in m1 + m2. for initials uh It is represented. we are for the final Let's take v as a representation. OK sir. A question is coming before us that carriage of a mass 9000 kg moving with a Speed 36 km. But our collide first of all this 36 Km But it is in the hour. You won't enjoy it. Let's convert this into meters per second. 36 in multiplication 5 / 18 so 18 * 2 is 36 36 and 18 is 2 okay? This is 10 meters per second 5 / 18 at 10 meters in multiplication Running out of seconds. this velocity gives us It is given in the question. it's on 10 meters Seconds. 10 meters per second. and in the story Read that there is a collision with a carriage of the same mass Used to be. after the collision carriage get coupled And move. Both are going on side by side in collision After. It means walking together. Just after the collision. if both together So what type of collision is this? will be? Inelastic. Perfectly Inelastic It will be of type. and give its common velocity It has been kept. That is what we do. and the same velocity We have to take it out. So what type of collision? will it be done sir? Perfectly Inelastic Collision The case with e = 0 will occur. and here v days can be removed m1u1 m1 + m2 see m1 initial in + m2u2 divide by m1 How much mass is in it? 9000 its velocity How much is it? 10. The other one has no speed there is no, there is no velocity because Initially it was on rest, so I wrote There is no need. Yes, in the divide m1 + m2, So 9,000 + 9,000, mass of both is equal Isn't it equal? Just solve it and then have fun. The right answer that you get will be the meter per second I will get it in. How much will the answer be? Comment Write it quickly in the section. your calculation So he is much faster than me. Write a comment Answer in the box. Is this the answer coming? At 5 meters the second is getting halved. 5 meters per second. The answer that should come here is will be 5 meters per second. It will be halved. Yes Yes. Ok? Best. Will you understand things? Will you understand things? There is no confusion No, son? There is no confusion, right? is coming Do you understand things? for two questions I have asked you to answer in the comment section I have asked for it. Right now these are the collegians For. What is? One. So this is different for the story. C told that inelastic collision will occur then What is? NCERT question was different. I asked, that is different. and one more question Now I am giving two bodies a and b have a same have a mass undergoes the completely Inelastic collision. returns e = 0. back Sir here e = 0. Ok? Inelastic Collision. one dimensional give a move with A velocity v1 was running away from the first v1. after both of them collide after both of them The body is moving along. Joe Velocity v2 I have given it. and asked you in the comment section given that what will be the answer of v1 / v2 Of these? Out of these you will be asked about v1 / v2 What will be the answer? so it's all about the work, Energy and power that helps get a lot of work done all the talk, lots of talk about energy and Lots of talk about power. Its concept very amazing work energy theorem which class It will be useful in 12th also. Vertical Concept of circular motion and the last one Collision is a big chapter in itself and In this big chapter I have given you two Small questions were given for homework If yes then son, write the answer in the comment section let's go. It could be that a lot of things I am trying to demine you. You are trying to outwit you. Very There could be all the reasons why I am suffering from this disease. Because of that I became a backlog. I School I was not able to read it. I have this disease because of which I was unable to read Had been. so there is a 99 reason why could be Are. And I am saying that there should be 999 reasons I might have given up. But you A tool to lift you up and get you growing Reason is enough. stick to that region and Write in the comment section that I am I stayed till the end of the video. Is it okay son? So this is where we end today's session. Are. Where everybody gets confused, Your master ji starts from here. Will meet Next time with new things. till then For you son, tata bye-b love you all.