1. You push very hard on a heavy desk, trying to move it. You do work on the desk:
(a) Whether or not it moves, as long as you are exerting a force.
(b) Only if it starts moving.
(c) Only if it doesn't move.
(d) Never-it does work on you.
(e) None of the above.
2. A satellite in circular orbit around the Earth moves at constant speed. This orbit is maintained by the force of gravity between the Earth and the satellite, yet no work is done on the satellite. How is this possible?
(a) No work is done if there is no contact between objects.
(b) No work is done because there is no gravity in space.
(c) No work is done if the direction of motion is perpendicular to the force.
(d) No work is done if objects move in a circle.