本题目来源于试卷: Physics Unit4: Force Dynamics & Newton's Laws，类别为 通用国际物理
[单选题]
It's more difficult to start moving a heavy carton from reskeej 8 cgcfm0h5 p9),mt than it is.q9t0eqval* (pp x 8y*wz8fri to keep pushing it(8axpy8l9v wiz.efp 0* qrtq* with constant velocity, because
A. the normal force is greater when the carton is at rest.
B. ${\mu}_s < {\mu}_k$
C. initially, the normal force is not perpendicular to the applied force.
D. ${\mu}_s > {\mu}_k$
参考答案: D
本题详细解析:
暂无
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