Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher

A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.

Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy eventually? Is it a violation of the law of conservation of energy?

An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?