試題詳解

36. Nadal received a shot with the tennis ball (60 g) travelling horizontally at 50 m/s, and returned the shot at 60 m/s horizontally in the opposite direction in 0.02 sec, what is the average force that Nadal suffered during this stroke?
(A) 22 N
(B) 30N
(C) 180 N
(D) 330 N
(E) 550 N