A 2kg moves directly east ward at a constant speed of 4.5m/s along the east west line. what is it's angular momentum about a point that lies 6m north of the line?​

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.