本题目来源于试卷: Typical Forces，类别为 美国物理杯赛(Physics Bowl)
[单选题]
99.32: A wooden box i mq)9ac2 i2u1sb*mgvps )bbc:zmv4i 5u first pulled across a horizontal steel plate as shown in the di c:b vmubz54)i agram A.
The box is then pulled across the same steel plate while the plate is inclined as shown in diagram B. How does the force required to overcome friction in the inclined
case (B) compare to the horizontal case (A)?
A. the frictional force is the same in both cases
B. the inclined case has a greater frictional force
C. the inclined case has less frictional force
D. the frictional force increases with angle until the angle is $90^{\circ}$ then drops to zero
E. more information is required
参考答案: C
本题详细解析:
暂无
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