試題詳解

10. Two equal masses are raised at constant velocity by ropes that run over pulleys, as shown below. B is raised twice as fast as mass A. The magnitudes of the forces exerted by masses A and B are, respectively, F_A and F_B, while the power supplied for each is P_A and P_B. Which statement is correct?
(A) F_B =F_A；P_B=P_A.
(B) F_B = F_A； P_B=2 P_A.
(C) F_B=2 F_A；P_B=P_A.
(D) F_B = 2 F_A； P_B = 2 P_A.
(E) P_A = F_A； P_B = F_B.