8. A rock is lifted for a certain time by a force F that is greater in magnitude than the rock's weight W . The change in kinetic energy of the rock during this time is equal to the
(A) work done by the net force ( F - W)
(B) work done by F alone
(C) work done by W alone
(D) difference in the momentum of the rock before and after this time
(E) difference in the potential energy of the rock before and after this time.
(A) work done by the net force ( F - W)
(B) work done by F alone
(C) work done by W alone
(D) difference in the momentum of the rock before and after this time
(E) difference in the potential energy of the rock before and after this time.