Question

A block is anchored at the centre of a circle and moves with a uniform circular motion. The pow of the force exerted on the block by the cord is

(a) positive

(b) negative

(c) zero

(d) not determinable

Answer 1

Correct option is (c) zero

Here, displacement and force are perpendicular. 

Work (W) = Force (F) x Displacement (s) 

= Fs cosθ (\(\because\) θ = 90°)

= Fs cos 90° (\(\because\) cos 90° = 0)

W = 0

Power = Work/Time = 0