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, FA and FB, while the power supplied for each is PA and PB. Which statement is correct? 
(A) FB =FA;PB=PA.
(B) FB = FA; PB=2 PA.
(C) FB=2 FA;PB=PA.
(D) FB = 2 FA; PB = 2 PA.
(E) PA = FA; PB = FB.
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統計: A(1), B(5), C(1), D(2), E(0) #3224656
統計: A(1), B(5), C(1), D(2), E(0) #3224656