A 2.2 kilogram cart is rolling along a frictionless, horizontal track towards a 1.2 kilogram cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a certain instant before the carts collide, the first cart's velocity is +3.3 m/s, and the second cart's velocity is -1.2 m/s.
(a) Find the total momentum of the system of the two carts at this instant?
(b) Evaluate the velocity of the first cart when the second cart was still at rest?