Question

Please explain ? Question 21.

Answer 1

`1/2 mga sin theta`

Explanation:

Since the block is sliding down the inclined plane at a uniform speed. the force of friction acting on it must be `mg sin theta`

The net torque on the body must be zero, so the torque of the normal force about the center must balance that of the friction (the weight of the block, assumed uniform, does not exert any torque at the center) which is equal to `mg sin theta times a/2`