Question

Concept of zero work and it's examples

Answer 1

work is zero if applied force is zero ( W=0 if F=0): if a block is moving on a smooth horizontal surface ( frictionless ) no work will be done... work done is zero when displacement is zero. This happens when a men pushes wall. There is no displacement of wall.

Answer 2

Or we can say that 0 work is done when the angle between the force and displacement is 90.

Sin 90=0 hence 0 work