Question

Why is the work done on an object moving with uniform circular motion zero?

Answer 1

Work done is equal to Force (acting in the direction of displacement) times the displacement i.e. W=F.S where (.) is dot product. For the work done we need component of force along the direction of displacement but displacement and force are 90°, at each and every point on the circular track and therefore the component of force along the direction of displacement will always be zero in case of a body moving in a circular track or a body performing circular motion. We know W=F.S or F.Scos$\left(\theta \right)$, since body is moving in circular track cos$\left(\theta \right)$=0 , and hence whole term will be 0 i.e. Work done will be 0.