Assignment:
Two blocks of masses M and 3M are placed on a horizontal, frictionless surface. A light spring is attached to one of them, and the blocks are pushed together with the spring between them (Fig.). A cord initially holding the blocks together is burned; after this, the block of mass 3M moves to the right with a speed of 1.50 m/s.
(a) What is the speed of the block of mass M? m/s
(b) Find the original elastic potential energy in the spring if M = 0.400 kg.
