Humpty Dumpty (5 kg) is about to a bungee jump from a 50-meter high bridge. Feeling nervous, he paces back and forth with a velocity of 2 m/s. What is Humpty Dumpty's GRAVITATIONAL POTENTIAL ENERGY before jumping?

Arailroad car collides with and sticks to an identical railroad car that is initially at rest. after the collision, the total kinetic energy of the two cars is a) the same as before. b) half as much as before. c) one third as much as before. d) one fourth as much as before. e) twice as much as before.