A rock is thrown off a tall cliff with a vertical speed of 25 m/s upward and a horizontal speed of 30 m/s. What will these speeds be 3 s later

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.