Question

Give an example in each case where work done by a force in zero positive and negative

Answer 1

work done
zero . if a boy is pushing a wall he is applying force but wall doesn't move hence work done is zero.
positive . a player kicks a ball then it moves force is applied and work is done
negative. fictional force is good eg of negative work done.

Answer 2

Example of work done positive- A man is pushing a box. Here the man pushing the box that is force. And there is also net displacement so the work done is positive

Example of work done negative- When a body falls freely under gravity , force gravity and displacement are in the same direction (q=0°) and the work done by a force of gravity is positive. Hence work done is negative.

Example of work done zero- For a body moving in a circular path, the centripetal force and displacement are perpendicular to each other. So the work done by centripetal force.