本题目来源于试卷: Typical Forces,类别为 美国物理杯赛(Physics Bowl)
[单选题]
95.34: A student pulls a wo b n+ese8f xk, gp8f13f(8xcylo :a4/ 1z(p y5ahuf ziczden box along a rough horizontal floor at constant speed by means hza1i5 u:( f/z4a czpyof a force P as shown to the right. Which of the following must be true?
A. $ P$ > f and N < W.
B. $P$ > f and N = W.
C. $P $= f and N > W.
D. $P$ = f and N = W.
E. $P$ < f and N = W.
参考答案: A
本题详细解析:
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