Two identical 0.50-kg carts, each 0.10 m long, are at rest on a low-friction track and are connected by a spring that is initially at its relaxed length of 0.50 m and is of negligible inertia. you give the cart on the left a push to the right (that is, toward the other cart), exerting a constant 4.5-n force. you stop pushing at the instant when the cart has moved 0.55 m . at this instant, the relative velocity of the two carts is zero and the spring is compressed to a length of 0.30 m. a locking mechanism keeps the spring compressed, and the two carts continue moving to the right. by what amount do you change the system's kinetic energy?