State and explain the work done in the following situation : A person carrying a heavy load walks on a level road.

State and explain the work done in the following situation : A man spending his energy by pushing on a concrete wall.

find out the sign of work done in the following cases: work done by an applied force on a moving on a rough horizontal plane.

Write the work done in each of the following cases as zero positive or negative. (a)Work done by centripetal force in circular motion. (b)Work done by friction. (c)Work done by gravitational force on a freely falling object. (d)Work done by the applied force in lifting an object.