## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

The work $W$ done on each cart is $W = F~s$, where $F$ is the force and $s$ is the displacement. Since the force is the same for both carts, and the displacement is the same for both carts, the work done on each cart is the same. Each cart starts from rest and the work done on each cart is the same. Therefore, the kinetic energy of the plastic cart is equal to the kinetic energy of the lead cart.