本题目来源于试卷: Work Energy and Power，类别为 美国物理杯赛(Physics Bowl)
[单选题]
94.38: A force F at an anvx r)qh:. l tiu:iv t;jks:-i)glesxgmval+ritd4 -4k7, θ above the horizontal is used to pull a heavy suitcase of weight mga distance d along a level floor at constant velocity. The coefficient of friction between the floor and the suitcase474 atg ,mlrk+- xsivd is μ. The work done by the frictional force is:
A. $–Fd cosθ$
B. $mgh – Fd cosθ$
C. $–Fμdcosθ $
D. $–mgμd$
E. $ –mgμdcosθ$
参考答案: A
本题详细解析:
暂无
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