A particle is moving in a circular path of given radius with (i) constant (ii) increasing (iii) decreasing number of rotations per second. What happens to work done in three cases.

Explanation

We know that the work done is equal to the change in kinetic energy of the system. Hence
(i) When speed is constant, K.E. does not change so , work done is zero.
(ii) When K.E. is increasing, work is done by exerting force.
(iii) When K.E. is decreasing, work is done by the body on the force.