## Net Torque on a Pulley

Question

The figure below shows two blocks suspended by a cord over a pulley. The mass of block B is twice the mass of block A, while the mass of the pulley is equal to the mass of block A. The blocks are let free to move and the cord moves on the pulley without slipping or stretching. There is no friction in the pulley axle, and the cord’s weight can be ignored.

A) Which of the following statements correctly describes the system shown in the figure?

=> The angular acceleration of the pulley is nonzero.

B) What happens when block B moves downward?

=> The right cord pulls on the pulley with greater force than the left cord.

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General Physics PRemastered 5 years 1 Answer 4096 views 0

## Answer ( 1 )

1. The cord moves on the pulley without slipping or stretching. Therefore pulley rotates as the masses movr.

The pulley has mass and therefore the pulley has moment of inertia.

There must be net torque which is responsible for starting the rotation of the pulley.

The net torque is resultant of two torques due to the two cords.

Tensions in left and right cords are NOT EQUAl

Tension in right cord is more because of the heavier mass of block B.

The blocks move with acceleration and pulley has angular acceleration .

Hence choice (c) is correct

(c)The angular acceleration of the pulley is nonzero.
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