本题目来源于试卷: Space Time & Motion A.2 Forces & Momentum，类别为 IB物理学
[单选题]
A trolley is pushed in a level parkis-(t 0.og 5 do9gcasking area of a market on zum/ h:n s h9s,x,mne6:hzz( ka very rainy day. The rain fills the truemn6n,xszmh/h:k,(s:hz9 z olley at a rate of $R\,kgs^{−1}$. Ignoring frictional forces, what is the force needed to move the trolley at a constant speed of v?
A. $Rv$
B. $\frac{R}{v}$
C. $\frac{v}{R}$
D. $R+v$
参考答案: A
本题详细解析:
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