Question

the work done is 100% when the applied force isacting at angle theta in the direction of displacement,what would be angle of applied force withdisplacement when work done is 50% ?​

Answer 1

Explanation:

When a body is whirled in a circle the work done is zero because in circular motion displacement  is always perpendicular to the applied force. Also when a body moves along a circular path then the centripetal force acts along the radius of the circle and is at right angle to the motion of the body .Thus work done by centripetal force is zero when the radial position does not change i.e when an object moves at  angle of 90 degree with the direction of force.

Work done = F.x Cosθ = F.xCos 90 = 0 (Since Cos 90 = 0)