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Let's start. Everyone ready? Let's go. Tell me the question.
Question number 54. Wait, I will find the answer. 54, Torsion's 54. We have done till 53 in the last class. isn't it now see the steege shaft a and b are used for transmitting power transmit the ratio of revolution of shaft na by nb is equal to 2 and the ratio of torque of shaft Ta by Tb is equal to half then Pa by Pb so Pa by Pb what will happen? Ta into omega a divided by Tb into omega b.
Ta by Tb is half and omega a by omega b is 2 so 1 is to 1 so that's why C is the correct answer tell me the answer quickly don't watch the video sitting here. Tell me the answer. Come on, tell me the answer to this question.
Very simple question. Very simple question. Here is a meter of distance on which the torque is applied. 600. How much is the total meter length? Total length is 1 meter from A, 4 meter.
So this is 1 meter and this is 3 meter. No, I will tell you. I have to make it for you guys. Okay? I am not going to tell you.
Hurry, hurry, hurry. Hurry, today I have to complete the entire chapter. It is the target. Until question number 99. Nobody is going to come here.
There is no one here. It's so easy question, no one is asking this question. It's very simple. Let's apply torque here.
Think with common sense. Here is more length and here is less length. If we apply torque, then where will be more reaction?
That is simple. Where length will be less, there will be more reaction. Here the torque will come, the resisting will come and here the torque will come.
Here how much happens? T into B by L will happen. And here T into A by L will happen. A is this distance and B is this distance.
So T into 3 by 4. or yet T into 1 by 4, T is your 600, 600 into 3 by 4 that is 450 or 1 by 4 that is 150, what will happen, so that is why A is the correct answer, so what will be A, correct. answer 56 strain energy in torsion office of per unit volume is given by ticket shaft may per unit volume it not a strain energy Hogan it not a strain energy Hogan per unit volume so guessing a carrier with a year QA square by 4 e with a name for you in a 4g So, strain energy per unit volume. So, strain energy is T square L upon 2gj divided by volume that is a into l. Now, so this is what we have to get. Now, we keep the value of t in the stress format.
Why? here it is given in the form of stress so what will happen in the form of stress value of t Q by D by 2 Q by D by 2 into j square into l into l divided by 2 g j a into L so L L is cancelled now see what else will be cancelled what will happen here? above 4 will be left and below 2 will be left so 2 will be left after that Q square will be left above J square here ticket Nietzsche d square G J a it now a chap ticket now J square head to JC a cut again clear up the here up Sarah values put so 2Q squared divided by G so it will remain now what will be the value of J?
pi by 32 d to the power 4 and what is below? d squared we are making some mistake d should be decancel What mistake have I made? G will cancel G What mistake have I made? D to the power of 4, D to the power of 4 will cancel Alright, pi by 32 d to the power 4 will be above, right?
d to the power 4 will be above, right? pi by 32 d to the power 4 This is d square and area's d square will be pi by 4 into d square Solve all this and you will get q square by 4g Did you understand? q square by 4g Is everyone clear? Ok, don't write only answer, write answer with question number Write answer with question number, then you will understand Whose answer you are asking, it is lag, there is a little lag on YouTube There is a lag in my teaching and answering your questions Let's go This question. For a section having an axis of symmetry, there will not be twisting if the load axis coincides with the symmetric axis.
The plane of loading contains. The bending axis. plane of loading will coincide with bending axis so the answer is B this is not a correct explanation explanation is that load is passing through shear center that's why there is no twist so if there is shear center on axis of symmetry if both axes are symmetrical then there is shear center on axis of symmetry so in that case load is passing from shear centre that's why twisting is not happening and this is not the reason so that's why B is the correct answer ok let's go 57 is not C it is B ok this question is easy the ratio of torsion moment of resistance ok of a solid circular shaft D and a hollow.
So, solid T solid divided by T hollow. So, J solid divided by J hollow. So, what happens if ratio D to the power 4 divided by capital D to the power 4 minus small d to the power 4. So, what will be the answer? A. That's why A is the correct answer.
Did you understand? 59 number. Tell me the question. 59 number. A solid circular shaft ABC has a total length 3A.
A geared wheel positioned at B at a distance A from the left end. Total length 3A hai. So this is A, this is 2A, total and 3A. So it is saying that A, B and C, how much torque will be there in A, B and B, C?
So now we will tell you. here length divided by total length and here length divided by total length so here 2 is to 1 ratio simple, nothing to do, no calculation to do by practice all these questions are made quickly all these do not need to be solved in the exam your practice should be such that all these things are done immediately in the exam ok thank you Now, let's go to 59 and 60. Tell me 60, there is nothing to do in this. Nothing to do in 60, just match.
Tell me by matching. torque twist relationship of for a circular shaft to a cut off or hojanga a cup for a big a dickly J1 or three miss a strain energy for elastic torsion strain energy for elastic torsion okay cons of over one or three obviously about the three over a C met theta squared RIA ticket or square a string energy met a evil over ticket see cut to circumferential shear stress circumferential shear stress is this. After that, maximum shear stress due to combined No, circumferential shear stress will be this. C will be 2. C will be 2 and D will be 1. Maximum shear stress due to combined torsion is this. So, your answer will be D.
D for DALI. 61. Tell me. 61. Dear Mains, before the exam, do not stop making questions. Reduce the time.
Make questions for 2-3 hours daily and do the rest of the time as per your vision. Stop making questions. question banana chhodi jayega na to ek break lag jayega question banate rahiyega to momentum me rahiyega exam ke din tak samajh mein aaya question agar banate rahiyega to exam ke din tak momentum bana hua rata hai aaya samajh mein aaya tikey hai bata yeh two shafts having same length and material are joined in series and subjected to a torque itna if the ratio of their diameter 2 is to 1 then the ratio of angle of twist diameter or angle of twist make your difference over so simple diameter or angle of twist so theta No, two shafts having same length and material are joined in series. In series, its diameter is more and then its diameter is less.
diameter is more and diameter is less so in series both torsion will be same so what will be the value of theta? theta will be T into L divided by G into J ok so the diameter is inversely proportional ok, now the power of diameter is not inversely proportional what happens in J? the power of diameter is 4 ok, so the ratio of diameter is 2 to 1 so What will be the ratio of rotation? Your 2 to the power 16 So, 1 is to 16 Not 16 is to 1 Why?
Because theta is inversely d to the power 4 That's why So, 2 is to 1 That's why 1 is to 16 Did you understand? Is it clear? Okay. Let's see. 62. Two coaxial springs are subjected to a force of 1 kN.
It is a coaxial spring. Okay. It is a big diameter spring and it has a small diameter spring inside it. Okay. larger spring diameter coefficient is 80 N per mm and the smaller diameter spring that is 120. So, see one is outer and one is inner.
When you compress, both will compress together. So, in both, compression value is same. Delta is same. This means this is parallel or series. So, this is parallel.
And if it is parallel, then net coefficient will be K equivalent. K equivalent simply add ho jayega. So, 120 plus 80, the deformation of the spring. So, delta kya ho jayega?
P by K equivalent, P 1 kilo Newton, 1 into 10 to the power 3 divided by 200. So, that is 5. Aaya samajh mein? Clear? Tell me this, when a cantilever shaft of brittle material is subjected to a clockwise twisting moment.
Clockwise twisting moment. So what will be the answer to this? Clockwise twisting moment.
Now, if you twist like this, then the crack that will develop in this will be like this or not? See, what is happening? It will be clockwise. So, if twisting is clockwise, then 45 degree clockwise with respect to axis of shaft.
That is the answer. As you may know. 64. The maximum shear stress produced in a shaft is itna.
The shaft is of itna mm diameter. What is the approximate value of twisting moment? So, P ka value nikalna hai. that is tau into j divided by d by 2. So, tau into pi by 32 d to the power 4 or here d to the power 4. Now put the value of tau, that is, tau's value is 5N, pi d will be converted into a cube, so the diameter is 40mm cube into 2 divided by 32. So, take out the value from this, what will it be? 63Nm.
Did you understand? 63 Newton meter Now Make this. This is a simple question I told you it is a simple question You just have to do this What will happen? Simple.
Max cut. So, its answer is D. Yes.
D is the correct answer. Okay? 66 number. This question is very simple. We have to get T A by T B. A and B's ratio is B by A is 1.5.
So, B by A is 1.5. So, T A by T B will be 1 divided by 1.5. So, that is 0.67. Will it be? A closed coiled helical spring with n coils mean This is the standard formula.
The value of the standard formula is B This is the standard formula. Just remember that it is written in the spring in the notes So, you don't have to do anything in this. You don't have to derive anything in the exam.
Remember the direct value of the spring 68 See what will happen Twisting moment M. What is the value of twisting moment? We have to find the value of T. Tau into J divided by D by 2. So tau that is 5 Newton per mm square pi by 32. How much? Put the value of the whole thing.
See how much it will be. The answer will be 62.8 Newton meter. Okay?
Good Badul, Good, Good, Good, Good, Good, Good. 69 number. What is being said?
Torsion applied to a circular shaft result in a twisting of 1 degree over a length of 1 meter. The maximum shaft is of 1 degree. shear stress induced is this much. We can do tau by d by 2 is equal to g theta by L. Tau's value is 120. What is the radius of shaft?
D is to be taken out D by 2 is called as radius G is given as 0.8 10 to the power 5 Theta is 1 degree, it is converted into radian So, pi by 180 will be radian Divided by L, how much is L? 1 meter, make it 1000 Let's make meter to mm So, from here only radius will be given What will be the value of radius? 270 by Pi In 66, it will be B Wait In 66, TA by TB Ok, B by A is given I made a mistake in writing hmm hmm hmm this will not be 66 this will not be 66 this will be this will be TA by TB so TA is equal to here is B so TA by TB is B by A so B by A will be 1.5 ok Faroon 70 I need to get the power out so power 5000 newton meter 180 rpm round per minute okay so 60 say three times thousands a divide for the Jato kilo pasta 30 so that's why D is the correct answer torsion is a very nice chapter torsion cassara question exam a banana okay torsion cassara question up logo see examine bunny 71, tell me the ratio of torsional stiffness torsional stiffness what will happen so simple T by J is equal to G theta by L. So, T by theta is stiffness.
So, G J by L. Once, what we have to get out of this? The ratio of torsion stiffness of hollow shaft to that of solid shaft. stiffness of hollow divided by stiffness of solid. So G and L are the same.
So J of hollow divided by J of solid. What will happen in J of hollow? I'm gonna cancel oh yeah yeah oh yeah yeah yeah so in each area so L is solid divided by l hollow and this will be d to the power of 4 minus small d to the power of 4 divided by d to the power of 4. Which answer will be? Solid y hollow.
I think it is C. No, it will be C. Solid hollow. Yes, C is the correct answer.
70 cut D 71 cut C good 72 72 a hollow circular shaft has more power transmitting capacity than solid shaft of same material and same weight per unit per unit length to stop capacity Java to keep Java with a ticket In a circular shaft, shear stress developed at point due to torsion is proportional to the radial distance. This is also correct. This is also correct.
But this is not correct explanation. Why? The J of hollow shaft is more. hollow shaft ka polar modulus jyada hota hai, jiski wajah se uska capacity jyada hota hai. To correct explanation nahi hai.
So, that's why B is the correct answer. Teekay? 72. 73. Bataiye.
If the shaft is turning at n rpm by mean torque to which the shaft is subjected to T, the power transmitted by the shaft in kilowatt would be? Kya ho jayega? Simple question. What have we made?
I don't feel like making it. 73 You people keep telling us, we keep ticking. What have we made?
Simple simple question. Tell me, Vadhun. Keep telling us, we keep ticking.
We will make the difficult question. You keep telling us quickly, we will fix it. 73's B. Good, good, good.
D will be there. Torsion rigidity is being said. G into J is torsion rigidity.
A solid circular shaft has been subjected to a pure torsion moment. A solid circular shaft has been subjected to a pure torsion moment. moment the ratio of maximum shear stress to maximum normal stress. So see, the maximum shear stress in this, suppose there is a stress element, if there shear will come.
Ok. Only torsion is applied and nothing else is applied. So if you apply torsion then only shear will come. So if shear comes then on any other plane, on its principal axis, your normal stress will be there.
Ok. So suppose this is Q. So draw its Mohr circle then will it be like this or not? So if we draw Mohr circle then shear stress Q, this is also Q and principal stress will be Q.
So ratio will be 1 is to 1. So this is the So, it's the ratio 1 is to 1. Directly. This is not being made. No problem. It will be made later. When we will teach principal stresses.
Make this. 79. 79 number Let's finish this chapter today. There is nothing left in this chapter. 79 number How much did it get?
It will get B It has no use ok, we have to get maximum shear stress so what is the value of tau? t divided by d by 2 see, d is given so j will also be given and t is not given so directly 4000 divided by 9 pi, ok good 80 number you have an idea a stepped circular shaft is fixed at a and c a or c fixed as shown in the diameter of the shaft along bc is twice either diameter 2d or either diameter d together torsion rigidity of a b is g j is 16 times GJ. Why? Because D to the power 4 is there. So, 16 times GJ is there.
The torque required for unit twist at B. Is it in series or parallel? It is in parallel.
Why? When you rotate from here, then both sides will be equal theta. Series does not happen by turning in parallel.
It is necessary to think that equal theta is equal to GJ. equal torsion so here when you rotate it will be same twisting and twisting clear so what you have to get is theta so theta is equal to T by J the torque required for unit twist twist unit unit twist so what happens is torque is equal to g j theta by l. So, g 1 l 1 g j 1 l 1 plus g j 2 theta by l 2 theta value unit So, take G out.
Take J out. L is equal to L. Okay. How much will this be? 1. And this will be 16. So, 16 and 1. 70. Did you understand?
It's a straight question of 81. Now, you have to get the maximum shear stress. Okay? P is equal to T into omega. I'll drop a P goal.
convert it as TAU into J divided by DY2 into omega we have to subtract TAU, rest is given remaining everything is given hmmm...its answer is 48 tell me vadhun, I am waiting for your answer 82 number same question nothing changed power will be 73kW just take care of unit in exam This is the answer to this question. It is hollow. Outer diameter and inner diameter are given.
You have to find stress both times. So, tau equal to T by j into R will be written. So, once R will be 8mm because diameter is 16mm. So, radius will be 8mm. And the second time R value will be 6mm.
So, keep it twice and take out the value. So, it will be B. 6mm and 8mm.
Yes. 84 84 simple question answer of 84 is 8pi very simple what will you tell us make it if you want to make it what is the power transmitted by a 100 mm diameter solid shaft at 150 rpm without exceeding a maximum stress of 60 newton per mm square What is the power transmission of this? It is simple, it is 187.5 It is simple, p is equal to p into omega, put the value of p tau into j divided by d by 2 omega put the entire value, just keep in mind the unit Is there power? No.
A hollow circular shaft of diameter this much cm and this much cm are subjected to a torque. If the realized maximum shear stress is this much, what is the applied torque to nearest unit? Okay, it is hollow.
So, the outer and inner are given. tau value is known so tau will be removed simple is the question what is it how much is it 80, ok yes 86 number question is wrong ok, 86 number question is wrong its answer does not match no answer is given, 640 will come 640 is the correct answer no option matches ok Rakesh, here we are making the question in the sequence of our workbook. So in that, the question of torsion, twisting and bending was given in the starting. So we have told it there. Okay.
Watch one lecture or two lectures first in this playlist, then you will get it. A circular shaft rotates at a power transmit. How much power will it transmit?
10 pi Simple Power transmit Nothing to do This question This question is a good question Ok Make a torsional torsion diagram in this Ok See the torsion diagram It is twisting like this It is a positive equation negative and then it goes straight like this so if you want to take negative then take negative how much? 2150 zero to see the either I do you get the material for us a purchase video has a constant field yeah either the positive well to you either Jaya constant or fit this ticket maximum portion get now 1 900 walk it will 50 to 50 to maximum torsion a good tool 50 here ticket or diameter of the economy get another major car you're gonna throw us a simple Anna t by J equal to tau by d by 2 R is the maximum torque and J is pi by 32 d to the power 4. It is solid. But we have given the value of tau so we have to find the diameter. So, the answer is 47.3. 47.3 is the correct answer.
Did you understand? Let's make this. Simple question.
89 and 90 89 Good Vadum Good Tell me about 1989 89 Solve it yourself 89 B No, 89 A will come 89 A comes 89 A comes 89 A comes Padoon, you also see by calculating Rama's 89 B has come Rama's 89 B has come You check it We haven't done the calculation of 89. It may be wrong in the answer key. Check how much 89 is coming. How much 89 is coming?
a hollow ST shaft has outer diameter D and inside diameter D by 2 the value of D for the shaft if it has to transmit it not it not being a declaration good care So, B is correct. We did not do this calculation. We just checked the answer key and ticked it.
We thought it was an easy question. No problem, do it. B is correct.
There is nothing in this question. Now, 90 number question. We will have to understand this question.
Understand it well first. Read the question well first, then we will explain. okay two thin walled tubular members made of the same material have the same length same wall thickness and same total weight total weight same iska matlab hai ki iska cross section same over here so same cross-section area over so a 0 dash divided by a 0 double dash so is capo section area is capo section area same over with a particular tube, then only its area will be same. Now, what will be its area?
So, pi into diameter multiplied by thickness and what will be its area? Simple, 4 into a multiplied by thickness. We will find its area. This area is very thin. It is written as thin wall tube.
Now, we will find the relation between diameter and A. So, what will be the diameter? It will be 4A by pi. It will be 4A by pi. What is it saying?
The ratio of shear stress. for the circular member in relation to a square number to circular member or a square member relation to the key is the torsional capacity kia hotel torsional hotel two times tau a mean into T this mean is the whole area of this circle this is not the area of hatched portion this is the whole area of circle and square so see circular area so tau of circular divided by of square so tau of circular we will write t divided by 2 area mean of circular into t and here what will happen t 2 times area mean of square into t ok now t t cancel 2 cancel T and T cancel. So, A mean square. A mean square.
So, what will be its area? Simply A square. So, the area above will be A square. And what will be its area below? 4a by pi square.
If we write d square, we can write 4a by pi square. If we solve this, we will get pi by 4. pi by 4 means this. Did you understand how to make it?
Did you understand? Thin walled tube's torsion capacity. This is the torsion capacity of thin walled tube.
Okay? Let's see. 91. What is 91 doing? It is taking out strain energy.
So, here we have torsion. We will add strain energy of both. So, U1 plus U2. What will happen to U1? Torsion will remain same in both.
Length of both will be same. Divided by. 2gj1, 2gj2. Okay? So, this much.
How much will it be? Its answer does not match. Okay? Instead of 1.73, it comes 1.63. Okay?
Instead of 1.73, it comes 1.63. This is the answer. clear calculation I'm key at a scale 1.63 of a second three new year they clearly a couple 92 hollow shafts are preferable in prop propeller or shaft of airplane say you are the propeller shaft you're the house my hollow job at Chautau use of hollow shafts affords considerable reduction in the weight of the shaft for equal performance same torsion transfer Carnegie less same same power transfer Carnegie a a hollow shaft is Ota house cubit come with a toe job at China aeroplane how I'm a little bit come right now so that's why is the correct answer you know a solid shaft itna subjected to a top another shaft b of same material and of same length but half the diameter diameter half ogia or pehle mein diameter d then the ratio of angle of twist of shaft B to that of shaft a ticket to diameter half oh yeah so simple angle of twist yoga theta may up come to solar times d to the power for an unknown formula this is 16 times simple formula like a torsion formula see the see Now, 94. The required diameter for this is simple. It is of power transfer. There is nothing in these questions.
What can I tell you about these questions? 95. This is also same. 95 is also same. 12 is the correct answer. Okay?
There is nothing to do in these questions. What can I tell you about these questions? This question is complicated. This question is complicated. To make this question, a lot of knowledge will be there, a lot of higher level structure knowledge will be there, then its answer will be made in the exam.
This came in the exam. This is not a general question. The year it came, we were making its solution.
So what is galloping, ovaling, oscillation, fluttering? You will not know the solution until you know all the four things. So in MTech, what is galloping due to wind, what is fluttering, all this is taught. When you study the structure design due to wind, then only this question will be asked. Otherwise it will not be asked.
So just remember that flutter is the answer to this question. Same question. repeat or you have to repeat the question again in the exam, then you have to tick the box.
Otherwise, it is very difficult to deal with all these questions in the exam. Thank you. which one of the following statement is correct for the rotating shaft transmitting power higher the frequency PT Omega Omega but he got the torsion come on yoga so that's why B is the correct answer solid start what will be the shear stress when frequency it not taken If the shear stress is 70, then the shear stress is 30. If you reduce the shear stress by half, then the shear stress will be doubled. Now we have seen that P is equal to T into omega and T is directly proportional to the shear stress. So if you increase the shear stress by half, then the shear stress will be doubled.
okay so this was all about this chapter I'm look Monday coming in gay or Monday come to principal stresses currently ticket so Monday come no milk a Monday come no principal stress currently is it clear okay good night good night good night good night good night