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

We can apply conservation of energy: $K_i+U_i+W = K_f+U_f+\Delta E_{th}$ Since the system's potential energy decreases, $U_i \gt U_f$ Since the system does work on the environment, $W \lt 0$ Therefore, it is not clear whether $K_i = K_f$, $K_i \gt K_f$ or $K_i \lt K_f$ There is not enough information.