試題詳解

2. A 70 kg person stands on one end of a one-meter long board. The board is uniform and weighs 100 kg. How far is the center of mass of the system “person on board” from the person?
(A) 0.1 m
(B) 0.3 m
(C) 0.5 m
(D) 0.8 m
(E) 0.9 m