An electric heater is rated 1500 W. How much energy does it use in 10 hours?

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.

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.

What is the work done by the force of gravity on a satellite moving round the earth? Justify your answer.

An object of 40 kg in raised to a height of 5m above the ground. What is its potential energy? If the object is allowed to fall, find its Kinetic energy when it is half-way down. (g = 10 ms–2)

Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?