A block of mass m = 9.40 kg, moving on a horizontal frictionless surface with a speed 5.20 m/s, makes a perfectly elastic collision with a block of mass M = 19.0 kg at rest. After the collision, the 9.40 block recoils with a speed of 0.700 m/s. In the figure, the blocks are in contact for 0.200 s. a) What is the velocity of the second mass M after the collision?

b) What quantities are conserved in this collision? Explain how you know they are conserved!

c) Find the average force on the 9.40-kg block, while the two blocks are in contact.