$A$ body moves along a circular path. How much work is done in doing so? Explain.

(0) When a body moves along a circular path,the centripetal force acting on it is always directed towards the center of the circle (along the radius).
The displacement of the body at any instant is along the tangent to the circular path at that point.
Since the radius and the tangent at any point on a circle are perpendicular to each other,the angle $\theta$ between the force $(F)$ and the displacement $(S)$ is $90^{\circ}$.
The formula for work done is $W = F S \cos \theta$.
Substituting $\theta = 90^{\circ}$,we get $W = F S \cos 90^{\circ}$.
Since $\cos 90^{\circ} = 0$,the work done $W = 0$.