本题目来源于试卷: Typical Forces，类别为 美国物理杯赛(Physics Bowl)
[单选题]
08.20: A person pushes zp2l:3d (lwnua block of mass M=6.0 t ip:naz99:iu x+e8zlkg with a constant speed of 5.0 m/s straight up a flat sur :i p+ z :azi99neltxu8face inclined $30^{\circ}$above the horizontal. The coefficient of kinetic friction between the block and the surface is μ = 0.40. What is the net force acting on the block?
A. 0N
B. 21N
C. 30N
D. 51N
E. 76N
参考答案: A
本题详细解析:
暂无
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