Hello friends how are you All guys how are you all doing hello Hello good evening good evening good evening good evening How are you all how are you doing hey someone please tell us too brothers are engaged in the same ho how was your first class is absolutely first class Come on let's go in first class covered the chapter on Equillium which This was the first chapter of statistics in which we People saw equilibrium equations and they How to apply these different options Situations right so today we will talk about friction and its we will read the applications in which Friction only in statics problems Introducing the concept of the SEM We will solve the same problems which were in the last class We did it the same way in will solve the problems of equilibrium but with a tadka of friction right and Applications of friction in different cases are also going to read it ok so son this is complete The schedule is tomorrow, classes start tomorrow The first class was of Equillium, after that today friction will be truss tomorrow okay so these three Chapters are of your statistics after that Then the dynamics will start in which we First we will study kinetics and then Kinetics will read okay so far gin People also did not join Tegra Group I'll remind them again that Friends if you want to ask any doubts etc. If you want to discuss doubts then you can do this quickly Telegram channel which is Telegram group which yes you can join, okay so today we will What are you going to study? Mechanism of How Friction Dry Friction Works After that we will use Belt Friction Wedges Screw Jack is going to look at all these applications as well it will be ok it will be in DPP class yes my Brother, we have a little time There we are just DPP this PP that The rest of us keep doing this concept Do you want to study two or three new concepts? You just have to read the chapter no let's go So in the last class, I told you guys a what was the assignment given assignment one There is a three hinge arch, right, which is here There's a hinge here and here in the middle as well there's a hinge attached isn't it and Oh so sorry I mentioned this here I couldn't tell which one is A and which one is B So let me mention this and this E B Then calculate the reactions at A and B Isn't it how will you do it brother if You can draw a single free body diagram of this If you make it then what would you like to see You will get a reaction, one will come from here The reaction will come from here, after that one The reaction will be like this The reaction will be like this Direction of reaction, you can imagine anything can you do it, i will call him a x I will tell this to you and I will tell this to you I will give it to you, I will tell him one Biwa here there are four unknowns and We have only three equilibrium equations This means we need to make another diagram You will get it yes or no, you will not get everything from here so where is it going to be found from here what What can I get if I go to point B takes the moment If I am there then the moment of another wife is zero will go and the moment of a will also be zero will go because he is also passing from B I will get the moment of a and that of w We will get the moment, what is the distance of a from b What is the distance between 4l and w if 3l is what equation do I get here a * 4l - w * 3l = 0 so a will be equal to 3/4 w isn't it similar summation of if fy4 then b is w ba 4 yes that would be na a 3/4 and b w4 so here you get a w4 and b 3/4 is rotated i.e. that this answer is wrong isn't it C& d that's wrong okay after that a one and b is nil now a is another If you will not get bxx4000 from here then So what do you have to do for it, see what you do There is a pin stuck in the middle here, so this You can remove the pin if I remove this pin If I pull it, this one part will become one This part will be made so basically these two There is a different part which is connected to the pin in the middle if they are there then we will make separate diagrams for them Now you can make a diagram of both. you don't need this part either make a diagram or make a diagram of it ok so what do I do with this one I will make a diagram of this part makes a diagram of it yes something like this will happen did this happen to you b X this is your wife now I will send this to you would tell the point so since there was a pin stuck here Brother, there will be two reactions sex and seam where the pin was attached If I move the body away from there If I disconnect, I'll give you a Reactions will be seen from CX and Siwa Let's tell him that now his height is 1.5A and it's 2A this is the height is the distance from here to here this is 1.5 L and this is the distance 2 If I take a moment here at point C so it's cex and siwa's moment Zero ex multiplied by 1.5A will be equal to bewa malla by 2 a to b e x will be equal to beva in 2 ba 1.5 ie d ba f in 2 ba 1.5 so here you get b a How much will I get if D ba 3 and if B acre ba 3 If yes then how much will be the Axe? 3 poses Neither A is correct nor B is correct is it correct or not yes it is clear thing is clear, you should not do this similar question na gate This was seen in 2024 I get this question asked almost every year ok not exactly the same but it is like that There was only a few questions where three hinges were fitted There were two forces at the gate doesn't it mean the question in our class Let's do the same with similar question gate If he came in 2024, who knows what else is going to happen? the questions we are asking in class May such a question get stuck in GATE 2025 as well whether it is right or not then the concept of equilibrium So we understood, now we will come On to your next chapter, Ch E Friction is fine So let's see what friction is so basically what is the friction between me Brother, when two contacting surfaces are close to each other Try to move with respect Meaning two surfaces are in contact with each other and to move relative to each other If you try, a force is created the force that opposes this motion It is called friction force, yes now There are two types of friction Which two types does one have? Dry friction and one is weight Friction is now understood by the name Bhaiya You will have dry friction and wet friction what does it mean isn't it dry Dry means there is no lubrication yes there is no lubrication here There is no lubricating oil between the surfaces The surface is completely dry in wet friction What is the meaning of lubricating oil She goes in the middle, what difference does it make now when the lubricating oil arrives then The concept of fluid mechanics is also included there. If this happens then you guys don't know this weight friction When you study machine design you will Do you read it if you guys have read it? If you haven't read it, go ahead and Read Poge crash course will also have machine You will read the design of bey rings there There you will read the chapter on weight friction but In engineering mechanics we are dry let's read friction okay now dry How does friction work in the first place? we understand this okay so To understand this, consider a simple example let's say a box okay there's a box that's a placed on a horizontal surface okay and I don't have anything on the box try to move it by applying force remained the weight of the box is given I will apply some force on it and it will I'm trying to move ok here is a simple example, now pay attention when you apply force on this box try to move it If you do it then what will be the reaction on it It will develop if I have a free body of it If I draw a diagram, what will I get? Reaction forces will be seen once this is done first p and one more this is done its wait w okay now the surface it's resting on Two reactions will develop on that surface This is a rough surface so there are two reactions on a rough surface Your normal reaction will develop Now you will come to my attention, right? This is a very good concept There are questions on this concept in GATE too It came, maybe it came in X, not in A but it came in action when you move the body If you try to do something then it seems normal It is a reaction that instead of passing through the center, it shifts. it happens why does it shift because When you move it to the right side it will become obvious It's a simple matter, apply some common sense to this You will feel more pressure on the corners, right? When you grab and pull the box towards this corner There will be more pressure and on this corner If the pressure comes down then you will feel the pressure like this to see the way If you get it then the resultant will be Normal Force If we now have a single normal Take force, it will not pass through the center shift to the right side So you have a normal force somewhere here We will get to see this normal force let's say it ok it is clear what i am saying is normal Why is it not passing through the force center because when I move it to the right side If I try, the right side is slightly The left side pressure feels more If it comes less then that is why the normal force it shifts to the right side above it There was a question in the exam and some The kids also messed up and you were not free I asked for the body diagram, just this one I had given the question, I had told you to correct it What would be the free body diagram so one option I was passing through a normal first class centre So many kids put in the same option. that normal first person has to pass from center If you don't apply any force to it If the body has to move just like this If it was kept then it would have been near the normal first centre but if you grab it and pull it So the normal force will shift to the left if you pull towards g then it will slide to the left now since we are holding this on the right side it will go trying to pull an opposite Force will develop because there is a rough surface So due to friction an opposite force arises will develop which will prevent it from moving What will be its direction, which way will you direct it If you want to move to the right side then What will be the direction of the friction force Left Side I'll call this friction force F. i am ok it is clear now if We will make a graph to show how A interacts with P. If there is a change then what would we see? understand this carefully understand this graph It is very important then you should use friction You will understand the concept of whose graph we made are We are plotting the graph of P versus F, which means we If we keep changing the P and see that the P how will f change with us then we will what to see okay now pay attention please give me Initially when we apply very little force If you try to move your body then the body will move Can you apply slight force to one of the boxes? If you push it, the box will move isn't it there initially when the force is If the value is very low then the body will not move and if the body does not move If it does then it means in body equi brion The net force will be zero i.e. F will be The value will be equal to p What The value of a will be equal to p Initially when the value of p is very low and The body will not move at that time and whatever is there will be will be equal and opposite of that, that's why the body It is not moving no matter how much force you applied The opposite force is the friction force It seems like the body is not moving at all So initially son, as you like, you will increase the value of A accordingly there will be an increase So you keep increasing P and F will also increase P keep increasing, F will also increase, keep increasing P f will also increase will increase will increase will increase a The point will come when your F is and your Reaching maximum value will reach its maximum value it will be ok It is this which The value will be f that this is equal to me a multiple by A R A Is The Normal Force and M as is known S to fisheye off Static Friction is what it is or is it a constant value depends on the material For every material there is a value for it hey pat p 3456 Every material has such value ok for that so m s is non as to fish off Static The value of friction decides that What is the maximum friction that can be developed between two surfaces Son, this is the maximum friction Value From here to here, as much force as you have are putting There was as much equal and opposite friction The force was developing, that is, from here onwards Even the body was static but now after this if I calculate the value of p and if I increase it then what Now your friction force will increase further no be If possible, move your body after this point turn on so after this point if I read more If you increase it, then the body starts moving And as soon as the body starts moving The friction force which is there before the crash falls down and then becomes constant go although it is not the Atlee constant but we can guess that becomes constant This is the value is this i am k*n where i am k is What Cofinec The friction is from here to here the body It was static and what came after that was the body It has become dynamic, that is, the body can move started it's okay and when the body becomes dynamic That is, when the body starts moving, then we Let us assume that the friction constant It happens no matter how much force you apply The value of friction force will remain constant u k * n but when the body remains static So your friction force is on top of p It depends when the body becomes dynamic then the body friction is constant goes to m k * n but when the body is static then the friction force on p It depends on how much force you apply developed as much will be at this point Friction force at this particular point The value of is m s * n this is that point when the body just starts to move Isn't it right to just move the body at this point When the body is just about to move There is friction force at that time, right? The value is m s * n and when the body moves At that time the friction force starts hmm k n a is clear Everybody is just going to move, meaning move them I am not completely ready to do it You have taken a bath and worn new clothes and are ready there is friction at that time to move The force will be A*n but when the body moves If it starts doing this then the friction force will be m k * n it will be ok This graph is not made by the pen He did some experiments and On the basis of experiment, he did this the graph was made although in this graph there are many All the Ajmans are like one Ampan (we are took it here that when the body moves then the friction force is constant it happens in actual there is no constant when the body starts to move then The friction force changes with velocity okay but here we have asked If we assume that it is a constant then all these are fractions which was taken by Kulam so Kulam's which This is a model of friction, and its fraction is We call them the Laws of Dry friction is ok so law of draw friction What does the first law say that friction Force judged directly proportional to the Applied Load friction force is the applied load see it is directly proportional is this proportional What does the second law of friction say first? force is independent of area of This does not happen in actual contact friction force area of the actual depends on the contact but Here Kulam assumed that the friction The force is in the area of contact is independent and the third law says that kinetic friction what it is Independent of Velocity we people I guess you did it when the kinetic friction If it comes then the friction force will be constant would rather it doesn't happen kinetic The friction depends on the velocity but here in engineering mechanics We consider friction with these fractions Do yes this thing is clear to everyone yes it is absolutely clear it is not clear now see in the exam A very simple question comes up many times okay there are different exams in which na many people mess you up i am one Let me ask you a question, suppose a body OK Its weight is let's say 100 Newton is ok How much is the normal force developed normally I am writing this to the force right now Because what we are is for Newton If you are using normal force then I am n1 I will write it, okay, then normal force How much normal force will come, it will also be 100 Newton This will happen because the body will move a little in this direction The body is moving in this direction Now she is doing Mann Here, the value of MA is given to you. it is 4M's given to you 3 OK, now let's assume I A force of 20 Newton is being applied here and you are being asked that friction How much force hoga what is friction force what will be R the answer what will be yours see answer this would have been Someone or the other always messes up this rotten place in question from Also know what our first intus says The friction force will be in n means 100 in po f 40 but my brother Here you are only applying 20 newtons, right? If you only apply 20 Newtons The friction force generated will also be 20 Newtons Maximum friction force 40 newt Here the value is 40 Newton but I am using 20 If I am applying Newton then the friction force is 20 Maximum friction will not be produced unless Newton Force Joe hat this is 40 newtons so if I ask you how to calculate this What is the minimum force required to move Then you will get your answer It will take 40 newtons to move it What is the minimum force required? It is 40 Newton, right? Only after that this body will move now I will change the question now I'm going to apply 50 newtons of force here If I am doing this then how much friction force will be there now Son, if I apply a force of 50 newtons here If I am doing this then how much friction force will be there now now look here also people what does it mean do not sit What is going on in your mind what I am saying People are saying you are 40 plus, tell me your age are giving look at this yours put 50 very good brother You are celebrating Diwali in your own way I play na People are still not addicted to gambling friction force is being given take mine 10 more from me hold on come on my brother maximum friction The force here is 40 Newtons. later the body will start moving and when the body moves If it starts doing this then the friction force in n Will be done neither your friction force is what it is will go 30 Newton Yes the maximum friction force is 40 Newton Friction can't go over my brother It is not possible to reach 50 but when the body moves If you start doing this then the friction will fall below 40 What will be the force? It will be 30 Newtons Look here the value is 40 Newton But when the body starts moving then friction What will be the force of falling m k * n1 That means 30 newtons so this is the question no it has come in the exam it has come in gate It has happened and most of the people are facing this problem okay it's a simple question but There is a problem in this too, right? remember the concept remember this graph The maximum friction force is m a in n when the body is just about to move but If you apply less force than that then the friction the same amount of force will be generated and when the body If it starts to move then the friction force is will be constant i.e. neither the first Whenever such a question comes, first of all you Check to see if the body is moving or not she is not doing it okay let's ask a question now do good, there are more concepts available now Now the next concept is of friction angle What is friction angle, look at it You will feel a normal force on any surface We will get another friction force, right? Have you met me? The value of friction force from normal force is less because the value of m is power p2 is less than one, this is what happens okay so let's say there is a normal force is A and there is a friction force M a if we have these two a resultant of If you take it, will it become something like this? The resultant of both of these something like this will be fine many times what is there in the question You will get normal and friction forces separately When does one have to take the resultant instead of taking it If we do this, many forces are created okay you will understand it yourself that when to do this, okay so tension from now on don't take how will you know in the question okay so You will understand it automatically if you Look at normal force and friction force If we replace it with a single force That means the resultant force will be something like this Now this resultant force is normal The angle formed by the force this is what we call friction angle is ok what is this friction angle it is the angle between the resultant force and the Now what is the normal force and the friction angle? will be Brother, so if I look into this triangle f will be the end of me a divided by a is No pie will be the ages of me a divided bye aa aa will be cut then fai will be n ivers of me to this is known as Friction angle n evers of me now what is its importance it varies in different cases ok Like if you are majoring in engineering mechanics You will see the concept of friction angle Its use will be seen in three places So I told you that if you assume You need to know the normal force and friction force. You don't need to take them separately if you need both. If it needs to be replaced with a single force then That single force which will be resultant What will be the angle between the force and A? Pi make an angle, okay it's clear thing let's move on to the next concept The numerical above is very interesting Let's come to the next concept is the angle of Repos now what is angle of repos Look, suppose a inclined surface okay there's a body placed on top of it right now the angle of inclination is very The body is low and is falling down, isn't it falling? but if I take this angle of keep increasing the inclination keep increasing If I keep increasing it, I will get a point When this body starts falling down in my case A point has fallen very quickly, hasn't it? When this body starts falling down, look Right now the angle of inclination is low, it should be increased Look, it started falling down, at the point where The body is ready to fall down The angle at which the body is ready to fall down The angle at which the angle goes is called angle of Did you understand repos, did you understand it? there's a box okay let's say which is a placed on inclined surface ok then When When this angle is such that the box is just If it is about to fall down then we will measure that angle will say angle of Repose now carefully Understanding the value of angle of repose If we calculate it then what will we do with it free body diagram of a box will make it ok Now pay attention to what I say listen here The weight of the box is as follows If you get weight then vertical line Right one normal force from here and a friction force will come now I I am guessing that the box is just going to fall down if the box is just about to fall down then the friction force is just above on the side That means the friction force would be something As such will it come yes or no I call it n, I call it m a and what is this w OK Now I have to put some equilibrium equations here is the summation of So look, this is in that direction but both of them are inclined right If it is in X then it is in Va then these two to resolve the but if I do that to X and Y take it so along the surface and perpendicular to the surface then both of these are in x and va will go and you just have to resolve the dab Will it be beneficial or not? Resolve these two It is easier to resolve one than to yes so what do we do, we double it we resolve D whenever we If we resolve it, we get two components something like this is seen This component is called component and this is the san component Remember this happens, otherwise you would dance every time You must be wondering which kiss, which sign, which Which sign does not require so much dancing? memorize this okay look memorize some things You should not take everything to heart, friend Whether to take it or not, how have we ever been like this since childhood We have not always memorized it with complete understanding do we work no no today is the work of rote learning I have never even looked at my ego in everything don't take it, it's ok, just memorize some things So that you can save your time by using your brain it will take time so memorize this that whenever if we resolve it then the The component is normal to the surface is the cos component and is parallel to the The surface that comes is the sign component So now if we have a summation of fxxx.pro what is it to you will get w sa theta and m n are the two forces x Can I write this in direction? am w sa theta e i m n exactly Summation Of fy2 and n are the same two forces has it will be equal to w k theta equals t a here now in equation and divided by equation to do If I give it to you, what will I get brother, the equation is not divided If you buy two then double and double will be cancelled will go sine theta by cos theta will become na theta and here a and a This will cancel out and become m so theta will be equal to no ever of me and what is no ever of M Fiction Angle Right Angle of Repos is equal to function I understood the angle what did you understand Does this mean that if a body if it is kept on an inclined surface then till then it will not fall down until the angle is off inclination not equal to friction angle happens if the angle of inclination friction If the angle is equal to or greater than the body will fall down But if this angle of friction inclination If the friction angle is less than then the body will never go down It won't fall, yes if it has to fall Then what you need to do is push if this angle is less than the friction angle If yes then what should be done to bring it down You will have to push, then you will go down I am clear whether it can fall or not my point is clear talk Now let's move on to the series of questions Let's start, isn't it? Enough of theories The theory is do not start asking questions If we continue the sequence then the first question before you is this I concentrated a little bit on my mind and got some rest I will make it from ok the crate has a weight of 350 Newton & Co Fish of Static End Kinetic Friction R and pattu Respectively if theta is equal to 45 degrees and p i equals 4 100 newton d Friction Force on the Floor what is he saying it's a crate a box What is the weight of this plant? It is 350 Newton Given fit of static and kinetic friction is 3 and p2 is ok the value of th is given to you is 45 degrees and the value of pi is given to you 100 newton means by applying a force to it we People are trying to move you, they are telling you What is the friction force on the floor Develop Now what did I tell you about this The first thing you need to know in the questions is You will have to check if this move is possible how do you know First you will do normal floors First remove the normal force its ok I would call a normal person n1 So this becomes its free body diagram because it looks like an inclined floor So let's resolve this, right? this becomes 100 cos 45 and this becomes 100 Sign 45 angle 45 now Here, first of all, find out the normal force. How to find out the value of EV summation of ava e 0 by doing this will be equal to how much 350 minus 100 bit What is the value of 45 n1 Is 279 29 Newton is this coming everybody Are getting 29.2 is it okay Now I have to find out the maximum friction force I will have to check so if I am at maximum If I calculate the friction force then how much will it be The maximum friction force will be in and how much is given in MS 3 and how much is it 2792 then what should be the maximum friction force will 83 Fifth note of musical scale is it 78 or not 79 So this is the maximum friction force right now how much does it take to move it It seems like force is being applied on this place who wants to move it it's 100 cos 45 this is the force to move it You want to do it in the X direction, right? So to move this you will need 100 cos 45 I am getting how much is 100 cos 45 son what is it 100 cos 45 7.71 newtons bhaiya what is this move you will not get maximum friction force You are applying 837 maximum friction force You have 8379 Newton and you can work on it only If you are applying so much force then it will not move and if it does not move then F key Value will be 771 newton no if it's not moving then you The more force you apply, the more friction force will be generated [music] 7.71 clear yes it is clear Correct ok very good very very good okay Let's move on to the next question if the force that's here no it would be more than this meaning if this move If I started doing this then there would be friction force If you are in A then first try to maximize yourself You will have to remove the friction fuse and check that is it moving or not moving properly right let's move on to the next question Let's go ahead and make this question now. take a body of weight 300 newton i lying on Rough Horizontal Plane Heaving to Fit Off Friction Path Find The Magnitia acting at an angle of 30 degrees with Horizontal means we have to find out the force that can start it moving What is the minimum force required to move it She is being asked to ok so first of all we will free body of this We will make the diagram of the free body of the box Make a diagram quickly Quickly create a free body diagram of a box Look, there is a force acting on the box At 30 degree angle then its weight is Vertical At least normal force will be felt will come and the friction force will come, we will Trying to move to the left So the friction force is on the right on the side I will tell you ok how much will you wait Is Its force is 300 Newton and A now this is the inclined let's resolve this yes this will happen p cos 30 and it will be now look here he is telling you that What is the minimum force required to move it If so, what conditions will we assume? Son, we are amazing I will do it, it's just about to move So we are going to call the friction force here. write k m in a write down kya m * n write down Write the m*n what about the friction force because we we are moving as if this is just a move is going to do it, isn't it, at least this much force But we will have to make sure that it just starts moving Okay, now let's look at the unknowns here. What unknowns are you getting in an n1 and there is a p, the value of m is then how much is the So you are given the value of m Meaning you are only getting one unknown here two unknowns are meeting and So brother here you need two equations Which two equations will be a summation of f Both an E0 and a summation of EVA0 are applied can you solve this summation what do you get from off a e 0 you will find a force here, a force here Is neither will you get 3 and minus from here p cos 30 is equal to zero right so what have value will go p cos 30 divided byeth is ok then o what is it from eva ect 0 If I get it then I will give it to you 30 minus 300 equals 0 now the value of y and pick it up two times 30 divided by 3 p p cy 30 i 300 solve the value of tell me how much is coming Is 8858 Newton is coming What 88.5 Newton very excellent very good 8858 n yes very very excellent Great so just made a free body diagram Set up the equilibrium equation and solve it That means the concept we saw yesterday Even today we are using the same thing You have added a touch of friction, right? Nothing has been done yes let's move on to the next question On to the next question okay let's go to the next question next this is an excellent question what is given a body of weight 250 Newton is lying on a rough plane inclined at an angle of 30 degrees with the What is being said horizontally is a body whose weight is 250 newton which is a rough The hinge is mounted on a plane inclined at 30 degrees but inclined it is supported by a Force parallel to the plane Meaning, we have applied a force to the body Support is provided Find the Minimum End Maximum value of p for ch equilibrium can be what is the assist being said what happened Brother what happened what's wrong here My brother, it doesn't mean anything, come to your senses splash some water on your face and then make a question, even if it's okay you are Ajay Kashyap body of weight yes so what to say to yourself here that the body which is It is kept on an inclined plane, we We are providing support by deploying a force, ok You will need to know the minimum and maximum of this force. tell the value so that this block remains in equilibrium now First understand its concept that this is minimum and what is the maximum value Value Okay, I am not a force here. should I apply it in body equilibrium Let's see this angle 30 degree and the value of m is 25, not ivers off 25 is 14 pat something is ok means Okay, so 14 degrees brother, the friction angle is 14 degrees and angle of inclination is 30 degree So if I don't apply any force here So what will happen is it will fall down or not It will fall down, read in angle of repose if we knew the angle of inclination If the friction angle is more than then the body it will fall down so if I apply any force here If I don't apply it, my body will start falling down Meaning I have to apply some force here to the body Do you need to stop yourself from falling down for a few minutes? apply force to stop it from falling down will have to let us assume that it is the minimum The force is 100 Newton just for example Let's assume that the minimum force is 100 newton means if I am less than 100 newton If I apply force then the block will fall down 100 newton is the minimum force okay If I put more than 100 then it will be 200 If I put Newton then there is no problem 300 I will put it, no problem. Put 500, no problem. no, should I put 1000 So brother it can happen that the body is down It won't fall but will start moving upwards if I If I apply too much force then the body will will start walking up Yes, this means there will be a maximum value as well of P in which he will remain in equilibrium then Let's say the maximum value is 1000 Newton So if I apply more than 1000 newtons of force If I apply it, my body will start going up 100 If I apply less than Newton then the body will fall down I will go and apply more force than Hajj then the body will it will go up but if your force is 100 And if it is between 1000 then the body is not down If it doesn't fall, it will go up between these two If you keep the force in the block I think it will stay in equilibrium with you guys It has entered my mind what the concept is So here we have the minimum and maximum of p. If we want to find out the value then what will we do once we zoom in we see that it's just below is about to fall and one day we will wonder that it's just gonna go up OK is the case One Body is on the verge of Going down okay the box is just below It's right on the verge of falling down Now bhaiya I am already waiting here I am resolving it, I told you If the question of inclined surface comes then Resolve the weights It is ok to give no what is the weight here son it is 250 angle 30 degrees it will be 250 cos 30 this will be 250 sign 30 yes it will happen and ok now what is the case jaega body is on the verge of going So what will be the difference between these two cases? In a case when the body is just about to fall down then the friction force is your upward it will be ok how much is it I am So here your friction force is will remain upward and in the second case the friction May the force be your downward It will be okay, this will be the only difference between the two cases In So quickly tell me the value of P here. are you coming take x and wa like this are yes, first of all we People do summation of eva e 0 If yes, then the value of EV will come here 250 cs 30 Then when we apply the summation of f e g, What will be the value of P 250 sign 30 tell me by putting the value of minus 25 and even how much is coming is 7.87 how much is coming What 7.87 very Good means this is the minimum force of P if If the force is less than this then the box will fall down it will be fine Now in the next case we are wondering this it's just gonna go up now even the value will remain the same 250 cos 30 or summation of f a e 0 when you apply it here What will be the value of just put it in the equation There will be a small change here it was minus p2 and here if plus p2 becomes even then what is coming is mine Brother 1793 is coming what 179 Very Best of all, this is the maximum value from this If you apply more force the box will move upwards i.e. if the force between these two will lie between these two values if it stays then the body will not fall down it will go up it is clear what is clear What if the value of p lies between these two if it stays then the body will not fall down will go up, this will reduce the value of p will fall below and will be more than the value will go up body is fine it is clear ba very good very very Good let's go proceed to next question But let's move on to the next question, a great question. has two blocks A and B of wet no kilonewton and u Kilonewtons Respectively Are in Equilibrium S shone in figure two boxes are placed right a And this is already a bit of a big question I am telling you The value of A is the weight of A is 1 kilonewton and The weight of B is 2 kilonewtons, I am telling you is the fish of friction between the blocks and between the block and floor it means every The coefficient of friction on the surface is We have to find the value by which this box will move start to do The minimum value of p by which this box can move start to do give ok this is box a which is this Tied by a rope to the wall here But it's okay No Now let us see if we compare these two boxes If you draw a free body diagram, how many The unknown will come, how unknown were you, Baba? be careful Look, this force seems to be its weight Then its wait now the rope that's tied here Tension some normal force will come here will come and since we move it to the left friction when you're trying to do it The force will come to the right no it happened okay it's done isn't it kilonewton this is your 2 kilonewton I call it a b okay and that's it 3 a b that's it t Look carefully my friends these two Assembled free body diagram of boxes I have made it I have box A in it as well and Box B also OK if both of us have a free body together If you make a diagram then the difference between the two There is no need to use force between these two We need to take the forces that are coming It is not there, now how many unknowns are seen here are You need p A B and three unknowns are visible What and how many equi brian equations now someone will say that sir three equivalence equation but the problem is that the moment here that you don't have an equation here, nor is there a distance etc. are given in the diagram, tell me Is the distance given somewhere or not? Doesn't it mean that the equation of moment is formed here you can't do it, you only have two equilibria The equation is the summation of f a e 0 and the summation off eva it 0 so bhaiya you have unknown There are three more equilibrium equations, so there are only two Bhaiya, can this question be asked now? It cannot be asked now. so what does that mean one more free A body diagram will have to be made whenever such Another free body diagram is drawn So that's another free body diagram, we Which one can we make? Let's go ahead and make it Can anyone make a free body diagram Can you make a free body diagram? You can also make a free body diagram either make it of a or make it of b yours any one will work either make one of a or make one of b Let's draw any free body diagram. I'm free body diagram of b is okay right B's free body The diagram is just of B crossing A above it Remove If you want I will give you a free body Draw the diagram of the free body of B. Diagram Now see, since I can separate A and B, I am done, so in between these two, there is a Will there be a normal force between these two? also if a normal force comes then that normal We call the force A I will give ok Is And a friction force will come here as well This is how it happened to you p y a b 3A B na3 A Is this free body diagram clear to everyone? is this free body diagram for everyone It is clear, absolutely clear, right? I just removed the A from above it Only the free body diagram of B is drawn. When I remove A from above it, then A The normal and friction forces due to It will come, we will have to install it so we installed it na3 a now here I am summation of fy2 it will be complicated for me Making a Free Body Diagram Sorry Construct the free body diagram of A It will get complicated, right? will go okay this is a free body If I am the free body diagram of diagram A If I make it, will any forces come or not? Tension Tee a normal force will come from here and The friction force is such that Correct now let me resolve this here At what angle is it inclined at 30 degrees At 30 degrees from the regional it will become cos 30 and it will be done T Now I have two unknowns A and me what do you want to take out i don't want this I want the value of my husband to be here can I take it out after keeping it If you find out your value, then it is summation what do you get from off a one e 0 will get p 3 a e equal to kas 30 means a will be Divide by P is 3 no ok is then the summation of eva e 0 karle summation of ava e 0 If I do this then will I get an app Cy equal to 1 kilonewton now substitute the value of a here two cos 30 divided by 3 ps t sine 30 ectu 1 kilonewton so from here you will get the value of T I will get it, tell me quickly, tell me quickly 29 kilonewtons is approaching what 29 kilonewtons yes it's 295 kilonewtons let's say three take it to the digit it is 295 kilonewtons very good very good Now we can pick up this value and keep it here. okay we will give its value now here we If people put it then now make your question Now how many unknowns are left with us Look how many unknowns are left now, only two unknowns now survived no because we find the value of t Now we are left with only two unknowns, P and A B so now after solving this we will get P will you get it or not, take it out take it out brother First of all find out the summation of eva e 0 to a b will have to be taken out ok then summation off If you do eva e 0 then what will be the value of ab will go 1 PlusTwo Minuses 295 to 30 A B how much Gone 2 P 85 kilonewton ok isn't it so what if we do the summation of an exc 0 aayega p will be equal to 3 a b pty cos 30 tell me how much are you getting Is 1.11 kilonewtons approaching What is 1.11 Kilonewton is coming Isn't it 1.11 kilonewtons clear? is done it's very good very very good okay so Here the question is based on only one free body diagram You will not have to make another free body diagram If I want then first I will give you a free body made a diagram and before here I t After that both A and B We made a phi body diagram by combining t I picked up the value and from here I clicked p Okay, I figured out the direction of friction Son, opposite to the direction you are moving will you come, you want to move towards left then the friction will come on the right side that no and the right side will come on top of it then its top left side will come Let's move forward Come on now let's ask a ladder question, look Ladder questions are also very important As of now there are one or two in that gate I think It has come many times, maybe it has come only once The question about ladder is important but let's pay attention From Understand what is given to you, a Ladder Sus Uniform Weight of 400 newton uniform weight If we say uniform weight then weight is applied at the center Dena is Uniform Distributor Weight means you can put it on the center ok a ladder has a weight of 400 newton and rests against a Smooth wall at B The wall that is built here It's smooth, meaning there's no friction here I have got some really smooth paint due to which there is friction here It has become zero but there is friction here has happened How much 3 he is asking you to tell the angle at which this start slipping at minimum angle that the ladder does not slip means what are you I'll guess the ladder is just about to slip it will be the minimum The angle is No ladder we'll guess that just slip Whatever angle we get at that time, we are going to do it find the same angle OK is gonna Is let's make it make it How to make lo Bhaiya here I get a free body of ladder You will have to make a diagram of the ladder first Body Diagram make it suppose this is your ladder okay is this A B and here's his center of gravity I will tell you I will stay Yes, now the weight is being applied on the center of gravity how much weight are you feeling It is feeling a weight of 400 newtons OK Now what kind of reactions will they get? What kind of reactions will the ladder get, son? This vertical surface is smooth, that means you don't see any friction force here You will get only normal force but this horizontal surface Here you will also get normal force and You will also get the friction force of normal force Now this is the direction of friction force Understand carefully what will be the direction of when If this ladder slips then it will move backwards when the ladder slips like this then it will go away will go down and A will go backwards It seems as if it wants to go backwards then the friction force is coming forward it would happen right The opposite is that no such something is ok Now how many unknowns do you see here? Son, how many unknowns are there in this diagram? You can see how many unknowns are visible in total this diagram I see three unknowns here which a a b and theta this theta too so He is unknown, isn't he brother? He was also unknown. a a b and theta there three unknown and in We have three unknowns to remove how many equations are there three is three This is the equilibrium equation or the equation of moment We can make this moment equation can ok if I take its length to be l then it is A Batu and this will become El Batu right? how much would that be brother this will be l sa theta and this will be l kas th yes ok is now how was i First of all you take out n b and After that you take a pay moment First find A and B and then take the moment on A take it ok is if we Here if we do the summation of eva equals 0 then how much You will get it in this direction, there are only two forces A And 400 A will be equal to 400 Newton Yes And if we take the summation here off f a e 0 will do then a b will be3 A means 3 in 400 a b will be equal to 120 Newton yes isn't it Correct Look, I am calling him a great man that if you get up after splashing water on your face then this are not even mentioning the friction force It can also be applied on B as written here It is very clear that B is a smooth wall, isn't it? But no, I don't want to read it, I have no questions. We have to read a little, so straight away we can see the diagram look at it and pose a question for us Amazing powers, next super after sha Am I the hero or not? So come on son, what do you want to do now? But seize the moment The equation of the next moment will become a summation Off a at a equals to zero okay So son when you take the moment on A then there will be 3 A and A the moment of these two will become zero okay Is nb0 Newton's moment will come n b's moment Look it will come anticlockwise and bring it here Come on it will come anti clockwise mbc3 is ok and the moment of 400 is that The moment of 400 will come clockwise It will come to -400 * Now look at this total distance l th is one sec this total distance l cos theta If yes, then son, it will come to the center, right? 400 Newton so this is gonna be l but cos theta is it coming to the center na toy el batu cos theta will be OK, now we will find the value of AB. have already 120 so 120 a psi theta will be equal to 200 l cos theta now l l cancels out if we bring cos theta here then this is not theta it's going to be 200 by 120 so theta Tell me friend how much is coming Evers of 200 Ba 120 tell me how much is coming 9.04 degrees is coming What 5904 degrees coming is it coming or not very nice very nice Good Let's go to the next question Now go and see more of Krish Four here Those who are born are speaking straight away Turn it off please, oh my brother, the one I had made a question there on a surface If there is any question as to where the box was kept then you Can you guess the angle of repose? Is this a question like this? Can you see friend, this is a different force here It seems there is a different force here wait it looks like this in the middle means one If you study the concept then you will know it throughout the world will you fit it a little Friend, you will read a concept, that's why brother you should study well, listen with your eyes closed friend are you doing this in mp3 mode you have not put it somewhere because when we are reading the angle of repose If you were there, then see what diagram was there. It is necessary if you listen only in audio mode It won't work, you have to see as well as listen It is there as well, like what I am seeing these days It is happening, you know, we will do it after class No, if you give PDF notes then some people do you know what you are doing can't you see Reading blank PDF notes okay similarly there are some people here who He walks with his phone in his pocket and earphones on Brother, let's go and listen to the lecture Ramanujan is not that great You will understand it by looking at the lecture notes. You will understand only after listening to the lecture who will have to do both the jobs is my brother I am neither Einstein nor Ramanujan If it weren't there then what would have been the point You don't have to work so hard You will feel both, that is why when someone I am explaining it as an example, don't make it fit everywhere If any question like that comes then fit in there you have to do it don't fit it everywhere here that If anything is slipping then the angle of repose Put two were taught to me in my childhood where I I see something slipping off the angle puts the repose no if you're slipping on a banana peel then there put this angle on repo hey friend i will fall tomorrow Friend, I went to the banana peel angle of repose How much was yours? It was 59 degrees, less than that. if you had slipped on the degree then it would not have happened falls don't do that okay let's move on to the next question now this question See what Find the Smallest is saying Angle beta for which the uniform crate can be Tip Corner a pap is saying i want to tip him what does it mean brother tip tip what does it mean to tip rainwater What does Tupping mean, Tupping means There is a body which is there in a corner like this Suppose it has come and stood on the edge This is the body, I am moving it like this If it stands in a corner like this I would say that it is sliding and it started toppling, then when in the body If there is tipping then the whole thing is normal I have force and I retreat to a corner I told you, didn't I, that the normal force is Right shifts to left as I I will try to move it to the right side then the normal force will shift to the right side So it would shift if the normal force were applied suddenly If it reaches such a corner then that condition it is called tapping ok so as soon as you type in the question Let's see what you have to do, normal Just need to put the force in the corner Have to quickly do its free body diagram Draw the diagram and place the normal force in that diagram. crept into the corner give it to me quickly So this is my box OK I am applying force on it I don't know the value of hmm yet The mass of is given as 100 kg and that of g The given value is 10 so what is the weight bro 1000 newton ok since now it is here You will put it on A Two felt Will you give it to me, should I say A, friend? Put it on A It is happening right, let me tell you the value of it. I have given it to him, I would have called it a pat Now whatever is there is inclined towards me. If I don't like inclined force then I will use this Let me resolve this angle is beta This ray is making a beta angle with the horizontal brother we will tell him p cos beta we'll say p sign beta okay Now here we see so many unknowns Three unknowns are seen A P and How many beta equilibrium equations are there? There are three Distance given two meter two meter two by If there is a box of two, then brother, I have three here. Equi Brion the equation is ok it is ok that no it's two meters this is also two meter is ok what is the first thing you do First of all, this point which we will call a they are speaking No, if I call this point B then B you would have taken a moment at the point what will happen sir from that P will not come in the equation, moment of P is zero na p sine beta p cos beta of these two The moment happened, Zero A's moment also happened Zero left P2 A and What will be the moment of 10002 A multiplied by A Bye The sum of 2 and 1000 will be inverted to be 1000 Multiply by how much will this distance be Brother, this is a total of two meters, this is being installed at the center If it is there then it will be a forest So what is the value of A you get from here? it is happening friend 1000 divided by 4 how Much 2500 newton is it's a 2500 newton very good friend very good now what should I do now We have to do the summation of f an e 0 and summation Off fy2 a and p cos Beta then it will be 2500 * P2 500 new is coming What will come from the end summation of Ava E 0 Tova has three forces au and pa sign beta p sign beta plus 1000 mine a is equal to 0 right p psi beta p 1000 - a how much p sign beta is coming from here son how much is sign beta coming from here 2500 minus 2500 value 1000 1500 Newton now It just became yours What was my job to do? To find out the beta it was just the equation one divided by fix the equation my brother Dividends two p sine beta ba p cos beta p p cancel there will be 10 beta and it becomes 1500 or 500 jaega beta will be n evers of 3 tell me brother how much is coming 71 P 565 degrees What so much 71.5 65 The degree is very good my friend, very good very good you guys are doing very well today At once awesome 71.5 65 did you understand the degree As soon as you see the mention in the question What you have to do is concentrate the normal force I have to take you in whichever direction the body moves If the body is left in that corner If you were moving sideways then it would be normal The force goes to the left corner ok Is Neither do I think the basics of friction This is a question, you guys can make it easily will you make that Otherwise, now we will discuss applications of friction Now let's go to applications Let's go off friction hey my brother Moment at A has to be made zero there which I have to make an equation, you should make it my friend ask why didn't he do it It would be better if you try it yourself and see who you are He is refusing everything, should I tell him? Let us now come to belt friction p now belt what is friction is the belt friction, i.e. When the friction force on the flexible belt what happens when it comes right is the value Take it a rod over which is attached a flexible belt This is a flexible belt There is some weight on one end of it We have applied it and at the other end we have some force are applying if the values are Take this rod and the belt between which there is something No friction in that condition on both sides of the belt what would be the tension would be equal to there is but If the friction between the rod and the belt Force In that case, the tension on both sides is different it happens why does this happen to me If you understand with the help of diagram then it means take this your belt Suppose such a There is a circular surface on which the belt is fitted If it has happened then we will tell you the color of the belt and would take it let's say the belt is something like this apply it okay from this point to this point and there is contact between the surfaces it was ok so this is the angle that is being formed no, we call this angle the angle of contact is ok now See how these forces will be created This is the belt, thank you so much brother, thank you So much this belt if I wear this belt be careful Let me make it a little bigger now showing I have a belt like this No, there is such a tension on this belt okay then between those two points It is coming in contact with these two points Will you get the normal force in between will get No, normal force in this way What is distributors force no this is normal force What is Now if you look at this diagram carefully Look, I haven't done any friction force yet have taken So if I just look at this diagram carefully, If I look at it, this diagram looks very symmetrical. What is happening at both the centers That means the tension on both sides will be the same will such a bean come both Same tension on either side will come but if we assume that both these surfaces be the friction force between and Let me move this to the right side I'm trying to do this so the friction is left will come towards Is the friction force towards the left Now what diagram will you see symmetrically It is not there brother, now if I go to the centre I can see both sides, the diagram is not symmetric So now both these tensions are not equal. will happen yes and no this There will be more tension here and How will it reduce for you sir know hey my brother this friction force left is coming towards so add this and this then it will be equal to no it is not that There is no tension in the direction it is moving I had guessed that it would be more I am trying to move in this direction, right? I guessed it was trying to move in this direction that is why I have called the friction force as I took it towards the left, so brother this The direction you want to move to It will be too simple, okay brother right There is more tension on the left side Now between these two tensions we have to face tension A relation is obtained by derivation because We have a crash course in this time I will not do derivation, I will directly establish that relation write Maximum Dividend Byte minimum equal to e to the power yes theta what is theta is known s the angle of contact and it is always the radius should be in degree not in okay 180 degrees equals pi radius na no ok so son this is the relation between tea max endt min t max byt minimum e equal to e to the power m theta r Theta is the angle of contact, which means that the two Is it in contact between the points? His If the angle is correct then you will get relief from belt friction You will get to see the questions in it, you just All you have to do is use this relation Is it easy to ask a question? okay now on top of that I'll give you a I will ask you questions so that you can get all the questions will become clear meaning of belt friction All the above types of questions are clear to you. I will go with one question, okay let me do just one The whole concept will be cleared by this question You just have to remember this formula. Maximum by Minimum Equation to the Power M Who has to take theta maximumt minimum It is clear who has to take the belt on which side is moving in that direction T maximum and t on the other side Minimum is fine, right? Let's ask this question. The question is an excellent question, what is being said? The block of weight 100 newton is supported bye a rope is rope and half times around the Circular PEC Determine the range of values of P for Chuch The Block Remains At Rest Coefficient of Static Friction Between The Rope and the Peg what is he saying, if pak says this then understand So this rod that has this rope on it It is wrapped one and a half times na and half times one and half times ok I am telling you that there is a weight on one side how much is 100 newton I have applied some force on the other side now The minimum and maximum value of this force I have to tell it so that it stays in equilibrium now Here the concept of minimum and maximum is same I have arrived Son, remember what I said about minimum and maximum I told you the concept, what did I tell you? If I said minimum force What if I don't apply any force here? the weight will fall down neither if I could stop this weight from falling down If you want to stop then apply some minimum force but if I use too much force If I apply it, the weight will not fall down, it will go up If it starts then the weight will not fall down If you want then the weight should go up then p's There will also be a minimum value and a maximum The value also how to take it out do you have Not the same one with T maximum and T minimum Have to use the formula but twice One bar you to replace the maximum you will keep it and once you replace the minimum You will keep this much but sir how much is it yes my brother here how many times have you tied the rope I have wrapped it several times, I have wrapped it several times right? Once I am fully wrapped up, my How much theta will be formed in 360 degrees no, when you wrap it completely once Suppose we wrap the angle completely once How much can be made 360 degrees or not my brother if I did this one and a half times how much is the wrapped angle is the bun 360 Look, it will be wrapped 480 degrees and one and a half times. Once it is fully wrapped then it will be 360 degrees that would be 2 pies and a half bar wrap Pi th Will B Pie radian 3 pi radian one wrap around means 360 degrees i.e. 2 It's a pie, right? Wrapping it halfway means 180. Degrees means wrapping pi one and half times 2 pi + pa 3 pa okay so Come on now what do I have to do once t p is to be taken in place of maximum and t in place of minimum If you want to take the place then this will be your p Divide By What is the value of 100 m given turn the pot upside down once Now just tell me the value from here, brother how much is coming it's coming 6586 Newton and it's coming 15 P 18 Newton means if it is less than 15.1 Newton then the weight will fall down and if If the weight remains more than 68.6 then the weight will go up will go but if your force is between these two If it stays in the middle then the weight will not fall down no it will go up ok it's ok clear All you need to do is rely on belt friction Now you have to do this only if the question comes in the exam Neither will you be bogged down by the question either the one who goes up will give both I will not ask any question here I have said the same thing I've done it, okay, let's move on. Now let's come to our next concept Veg is not a different concept in veg basically what is veg Judge is a very simple lifting machine Judge Joe it is a simple lifting machine which we call People use heavy things to lift it up with a little less effort Usually this wedge is for moving, isn't it? it is made of wood meaning Its weight is very negligible This happens, that is why we usually weigh the wages If you neglect what is there then respect Here is a heavy stone to lift it up for we saw one such wooden piece of wood stuck in it which is It's tapered so just like we guys use wood This will keep inserting the piece inside The heavy stone would rise a little It will go up a little bit from the ground, right? can have If not, then you have a question about veg. Only normal people will come, there is something different in this I don't want to apply the concept, ok which type Questions may come up, so let's look at a question is the coeff of static friction between the 1000 Newton body and the wedge e Put means this 1000 newton body is capable of This wedge is the best way to lift you up This surface between these two is fine Its cos of friction is given hat the rollers that are fitted here these rollers There is no friction in these rollers there is no friction okay i am telling you What is the minimum force to be applied This angle is given, 15 degrees is correct What is the minimum force to be applied it will be ok is now carefully See if we can get both of these for free together If we draw a body diagram, how many you will meet the unknown Come on let me give you If we take these together, then the free body diagram is Make such a diagram that it will look beautiful Like no it's haj newton You are applying yours from here p ok This is a normal reaction from here will come and a normal return from here Now understand this carefully, because here Usually a doubt arises Sir why is the normal reaction coming from here why is it not coming from here There is support on both sides, look my brother Reaction happens when there is an action Meaning when it applies force on the wall then it will change the wall will apply force on it now will it do so It could be on the wall on both sides. Apply force and lift a stone up If yes, then either it is adjacent to the wall on this side will he rise up or else he will sit on this side wall The stone will rise above the exp that it will apply force on both the walls can the stone which is there be spent It seems that there is some force on this wall too and apply force on this wall also then when If I insert this, it's 1000 Newtons. The stone which is there is pressed on this wall If it gets pressed and rises up then it can be done only from here You will get a reaction, not a reaction from here you will get it because this extension is not happening that from both sides reaction okay now here you will get total how many get to see the unknown I am watching three unknowns to ev a and how much is the equation is the sum of f a e 0 and sum of eva e 0 then We have three unknowns and two equations It won't work, that means I need another Creating FBD If it falls then my brother, the one who is the second FBD would make it is this for a body of 1000 newton This is Hugh Newton's force There's an A coming from here there's a normal force coming from here okay is now carefully see i will tell you n3 Now look carefully, this is an inclined surface How will the friction force be on it? Brother, if I move the judge to the left If I am sitting then which side is the friction force on the judge I should move the judge to the left So the friction force on the wedge is right should come towards What if the wedge comes to the right? the stone above F will come to the left in between the two There should be equal opposite friction If the force is moving towards the right then the wedge then it will go to the left over the stone The friction force here is If it comes then what is the value of m Pat what do I have to take out now? have to take out Now you have two choices, what are the two choices Either you can choose the summation of f one and the summation of ava Tax You can take it out from there as well or else i have another way what are you Do A3 and multiply A3 by a resultant replace do this i will tell you what is this y and m are the resultants of A3 which are at phi angles I think I remembered the friction angle I told you this concept on time Tha n3 and m is a resultant of A3 which is A3 What is the angle made by phi angle will make it and how much is the evers of me i.e. n eaver of pattu ch e 11.31 d Correct So my brother now I have three forces here showing n1 1000 and r3 now remove both of these now just r3 So take n1 1000 and r3 are three forces gone n1 it looks like this it looks like 1000 and r3 is n3 f is making an angle with n3 and n3 is making an angle with the vertical how much angle is being made What is the angle that n3 makes with the vertical? then n3 vertices the surface is making 15° from the surface, right son If the normal to the surface is 15° from the horizontal then 15° from vertical will make it remember i explained it yesterday if If the surface creates theta from the horizontal then the surface theta will make the normal of the vertical so this n3 which is 15 degrees from the vertical So son see how much is the total from r3 vertical Angle will make 15 + 5 i.e. 26.3 This is a3 s angle E 26.3 degree is ok If it is there then apply this oil and take it out Divided By What is the angle between the two signs? Gaya 180 mine 26.3 equal to 1000 divided Buy sign of the angle between these two how much is 90 plus 6.3 how much is coming from here son 4944 4 94.4 coming Is is 44.4 it is not clear what did i do n3 and replace n3 with their resultants Given resultant n3 is making an angle with f and n3 is making 15 from the vertices then r3 How much will 15 percent make in total from vertical 5 OK Now let me look at this free body diagram to solve then to find p you just need to do the summation of f is equal to 0 p will be equal to That is 494 p 45 Newton there is no trace of No 4445 newton ok If yes then you will see similar questions on Veg. I have also given it in DPP This is an excellent question, look at this, you guys are DPP You people know where to get DPP Isn't it true that in PW's paper you need DPP You will find the PW app there. You will not get a free batch of crash course The name of Gate 2025 is in that free batch You will get notes as well as PDF notes If you get it and you get DPP also then You will get only answer key in DPP Solution if you want to discuss I have provided the link to the telegram group right, I gave it in the beginning as well, just now in the end I will also give you DPP on telegroup can you discuss the solution with anyone If you have any doubt in any question then you guys You can ask, okay, did I make a mistake here? did it is y and two kids were distracted hey how did it happen like this how did it happen like this n1 is n2 don't go Ahead Grow up son, you will never get DPP You won't get it, I don't understand it Brother, I don't know what you guys mean by engineering something may happen in second year, third year and final year People are droppers, even then a pap I can't find a PDF that makes sense you are doing this, it means you have to tell everything that Son first go here then click here Then click on the name of the technology there P not at all Now like this Dabba Jabba brother means how can this happen oh my god A Siri type prisoner came from inside Whatever you want to tell, son DPP is here You will find it there, you don't have to open it and look for it Is Naa open it once and take a look at it a little Explore it for 10, 15, 20 minutes Give me some time and you'll understand everything No one can make it so complicated Yes brother, the PWD people understand it. I can't figure out where to get what hey look at it friend Come on, don't take it to heart brother, nowadays there are such people have become so super sensitive that anything If you tell me then I start feeling scared that there will be no tomorrow again I came to know that some news is running on me. is is not let's go now the next topic is Scrooge one though Screw jack, according to me the exam points Not very important from the off view is there any need for numerical to come on it the chances are pretty low okay so I'll tell you Let me tell you about it quickly I have a chance of getting the numerical above There seems to be a little less on the topics They are more likely to get numericals I have explained it well I will explain a little quickly yes, you just need to remember one or two formulas in this if you have to keep it then what is the use of a screw jack This is basically the work of a screw jack There is a screw, turn it and it will go up Its function will be below, this is it If you spin it round and round it will go up and down So my brother, what are you supposed to do now? moving the weight up and down with the help of a screw jack OK Now this is the screw that is stuck in it threads are made These threads have a minimum diameter Is There would be a maximum diameter and has a mean diameter of ss i non S Core Diameter Min Diameter is not a nominal diameter Maximum diameter or your machine design I study well, I say ok Mean diameter which is the average of these two So whatever calculations you have to do And you have to do it yourself by using DM The diameter is given in the question, it is correct The angle at which this thread is, we call it helix angle speak as if it is thread no it is inclined at some angle so it speaking helix angle now there are two adjacent threads between them The distance which is there we call it Are The pitch is the distance between two adjacent threads The angle which is there is what we call it pitch now if I turn this screw a The bar will move up or down as much as the screw We call him a people lead now see if there is a single threaded screw means if a thread is coming from top to bottom then The lead and pitch are equal to this We call it single threaded screw But here you can see in the diagram gotta double threaded screw look here a lead This is one thread, but in the middle of it there is a The second thread has also entered so give it here Threads are coming from top to bottom Double is ok so double threaded screw if is given then the lead will be two times of Pitch is a question in the exam. I will keep giving it to you if you are not saying anything Take equal lead and pitch but if double If the threaded screw is written then the lead will be equal to two times of pitch simple Now understand carefully if suppose I am a to single thread If I look at it, it will look something like this what if i open this one Let me open a single thread. Let me open it. Can I get a diagram like this Narrate How much is this angle this will be the helix angle th ok This height is equal to lead It will be there and if D diameter if yes then how much will it be will it become padi, will it become a parameter, right? If you look from above then the thread is a circle will look like whose diameter is dm then If I open that circle then this length padi will be m then will i divide theta by l and I can write in DM's terms who can be written as an angel of a bye PADI Ah, isn't it? You have to remember this formula yourself. Gave myself A and D A in the question From there, you can calculate your theta theta will be no aver of a by padi A okay the distance lead between these two And if I open it then this distance will be covered then theta will be a null symbol of a okay now look at yourself no wait up and have to do below So if you want to elevate yourself then do the minimum How much force does it take had in 10 pie plus theta is okay and if do down the formula becomes w in 10 f min th Its derivation is But I've told you screw jack It is not a very important topic That's why just remember the formulas if you If you want to increase your weight then go for Fai Plus theta and if you want to bring your weight down so theta f minus theta here theta is always pi to be smaller than should be ok is for self locking pi must always be greater than theta self If we talk about locking then brother if pi and theta If they are equal then the value of p will be zero No, it will start falling down on its own You are thinking that the weight will automatically fall down It will seem like you are rotating it and taking it up As soon as you let go you will automatically fall down you'll want it to be locked when If I don't apply force on it, it gets locked If it doesn't come down on its own then it's your fault should always be greater than th so this self It will be called locking, meaning it will get locked when you twist it You will take me up by twisting and turning If you let it go, it will lock, not come down If it falls, this value will always be greater than zero i.e. phi should always be greater than theta If yes then remember these two formulas = w 10 f + theta p = w 10 f min Okay, now there is a question about its efficiency as well. There is a formula, remember that formula too Take it you guys It in theta divided by n fps th ok then you need to know two angles in total If you want phi and theta then phi is your friction be the angle and theta be your helix angle Gaya Naa Ivers Of A Ba padi ok na so son theta from here take it out by turning off the pan have to take if gaya is asking you to go up Find the force for this then this is the formula use force to bring it down so this one If you ask me about formula and efficiency then this one formula just remember the formula though According to me, there is a possibility of a question arising on this. unlikely to OK So let's do an assignment question on this I'll give it to you guys to try This is a simple question to solve is its solution our class tomorrow I'm ok So today we learned the mechanism of dry Read Friction Then I looked at the basic questions is for the naa then look at belt friction See also and also took the screw jack in a hurry why did you take it and looked in a hurry because Screw Jack: According to me exam points of you is not that important okay now look at you guys who are DPP which will be available in the app, let me tell you again I will give you a free copy of the crash course You will get a batch, you will go to that batch and you will get DPP You will get information about every subject here, son The DPP questions you are getting If you have any doubt in it or you need a class If you have any doubt you can send it on this telegram You can ask on the group Telegram group You have been given more questions, join them Ask without hesitation, it is clear, we can have crash course of all subject yes you can have crash course of l You will take the subject of Sam, right sir? Brother, if someone else takes it then there is no problem Will you study if no one else teaches you? What difference does it make if you read it, I'll see Has anyone else read it should mean teaching, it is about studying, right? Whoever teaches, teach well with all your heart You guys should not take any tension, right? You will get the best possible teachers for every subject If you get to see it then don't worry at all If I have time then I will definitely I will teach you ok hey let's go Now if you guys request so much then friend Then how can I refuse, right? Brother, I will teach you, no problem. It is just a little, what is the constraint of time it happens because what we have together There must be a lot of balances going on then We have to see who is free and who is free There isn't any other problem at that time, right? Let no one's health deteriorate right but if we are available then Ofcourse I will teach you guys No tension at all, okay let's go for today Let's end the class here, we will meet tomorrow We start the chapter on Trusses and Frames It is very interesting and very This question is also important almost every second year It comes in mechanical as well as automatic I am also fine so tomorrow Trust and Frames okay let's meet again tomorrow at the same time place ba bye take care good night