(1) Two railroad car collide and latch together. What quantity is conserved? What quantity is NOT conserved?

conserved? What quantity is NOT conserved?

(2) Toy Cart A has a mass of 3 kg and a velocity of 4 m/s to the right; Toy Cart B has a mass of 5 kg and a velocity of 3 m/s to left. The two collide and stick together. What is the velocity of the wo after the collision?

(3) If an impulse of 10 N-m is applied to a freely moving object, what is the momentum change of the moving object? Why?