Question

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

Answer 1

As work done = change in kinetic energy, hence, (i) for constant speed, kinetic energy does not change and work done is zero.

(ii) for increasing speed, K.E. is increasing, and work is done by the external force.

(iii) for decreasing speed, K.E. is decreasing and work is done by the particle itself.