Which statement best defines constructive interference? O Energy reflects back toward the source of its power. O Two waves with identical crests and troughs meet. thing O A wave appears to be at a standstill and vibrates in place O The trough of one wave matches the crest of another.​

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.