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 st5e0lwtxx /9b cart moving yk3 reu + dd7eh51)cqba heavy carton from rest than it is to keep pushing it with constant ved17+) ykeure3 cbq 5hdlocity, 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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