1. You push a heavy crate down a ramp at a constant velocity. Only four forces act on the crate. Which force does the greatest magnitude of work on the crate?
(a) The force of friction.
(b) The force of gravity.
(c) The normal force.
(d) The force of you pushing.
(e) The net force.
2. A ball is thrown straight up. Neglecting air resistance, which statement is not true regarding the energy of the ball?
(a) The potential energy decreases while the ball is going up.
(b) The kinetic energy decreases while the ball is going up.
(c) The sum of the kinetic energy and potential energy is constant.
(d) The potential energy decreases when the ball is coming down.
(e) The kinetic energy increases when the ball is coming down.