Question

A force F acts on a body and displaces it by a distance S in a direction at an angle $\theta$ with the direction of force.

(a) Write the expression for the work done by the force.

(b) What should be the angle between the force and displacement to get (i) zero, (ii) maximum, work?

Answer 1

(a) Work done by a force when the force is at an angle θ to the direction of displacement, $W=FScos\theta$

(b) (i) W = 0 when $cos\theta =0\Rightarrow \theta ={90}^o$
(ii) W = maximum when $cos\theta =1\Rightarrow \theta =0^o$