試題詳解

22. A pendulum consists of a 0.500 kg mass on the end of a light rod 50.0 cm long. It was set swinging so that the greatest angle the rod makes with the vertical was 30.0º. After 5 hours and 30 minutes it was seen to come to rest at its lowest position. How much work was done on the pendulum by the frictional forces? (Answer in J)
(A) – 1.225
(B) – 0.825
(C) + 0.450
(D) – 0.328