On a frictionless, horizontal air table, puck A (with mass 0.150 kg ) is moving toward puck B (with mass 0.400 kg ), which is initially at rest. After the collision, puck A has a velocity of 0.120 m/s to the left, and puck B has a velocity of 0.640 m/s to the right.
1) What was the speed of puck A before the collision?
2) Calculate the change in the total kinetic energy of the system that occurs during the collision.