Physics - Rotation Question with Solution | TestHub

PhysicsRotationTorque / angular accelerationHard2 minPYQ_2021
PhysicsHardmultiple choice

One end of a horizontal uniform beam of weight W and length L is hinged on a vertical wall at point O and its other end is supported by a light inextensible rope. The other end of the rope is fixed at point Q, at a height L above the hinge at point O. A block of weight αW is attached at the point P of the beam, as shown in the figure (not to scale). The rope can sustain a maximum tension of  22W. Which of the following statement(s) is(are) correct?

 

Options:(select one or more)

Answer:
A, B, D
Solution:

 

∵ Rod is in equilibrium, net torque on the rod about O will be zero.

Wl2+αWl=T2l

⇒W2+αW=T2⇒T=2Wα+0.5   ...1

 

Now checking options-

(A)

Force balance on rod,

Nv+T2=W+αW

⇒Nv=W+αW-W2+αW

⇒Nv=W2

Hence, option (A) is correct.

(B) Write horizontal force equation,

NH=T2⇒NH=Wα+0.5

If α=0.5, then,

NH=W and T=2W

Hence, option (B) is correct.

(D) ∴ Maximum Tension of string =22W

So, to break.

T>22W⇒2Wα+0.5>22W⇒α>1.5

So, string will break.

option (D) correct.

Stream:JEE_ADVSubject:PhysicsTopic:RotationSubtopic:Torque / angular acceleration
⏱ 2mℹ️ Source: PYQ_2021

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