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
答D
這題是一般鉛直的單擺？但為何算功，題目還會提到 時間呢？ 麻煩高手解答一下
不知怎麼算><
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If the angular velocity is 30 radians per second at t = 0, find the angle
turned through by the wheel between times t = 3 and t = 5 seconds.
Answer in radians.
(A) 260
(B) 320
(C) 380
(D) 500
答D
這題是求角位移是嗎？我的想法是，能否直接從角加速度往回積分，這樣就可算角加
速
和角位移？
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再麻煩各位大大 給予建議 謝謝~~~^ ^