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32. A 5.0-kg crate is resting on a horizontal plank. The coefficient of static friction is 0.50 and the
coefficient of kinetic friction is 0.40. After one end of the plank is raised so the plank makes
an angle of 25◦ with the horizontal, the force of friction is:
A. 0
B. 18N
C. 21N
D. 22N
E. 44N
ans: C
.
A 5.0-kg crate is resting on a horizontal plank. The coefficient of static friction is 0.50 and the
coefficient of kinetic friction is 0.40. After one end of the plank is raised so the plank makes
an angle of 30◦ with the horizontal, the force of friction is:
A. 0
B. 18N
C. 21N
D. 22N
E. 44N
ans: B
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