A 40-N crate rests on a rough horizontal floor. A 12-N horizonatl force is then applied to it. If the coefficients of friction are $\mu$ _s = 0.5 and $\mu$ _k = 0.4, the magnitude of the frictional force on the crate is: A) 8 N B) 12 N C) 16 N D) 20 N E) 40 Nb

Question

Quizplus · Accepted Answer

Since the force applied (12 N) is less than the maximum static friction force (40 N * 0.5 = 20 N), the crate will not move initially. Therefore, the frictional force on the crate will be equal to the force applied, which is 12 N. The coefficient of kinetic friction is not needed since the crate is not moving yet. Therefore, the correct choice is B.

A 40-N Crate Rests on a Rough Horizontal Floor μ\muμ s = 0

A 40-N Crate Rests on a Rough Horizontal Floor $\mu$ _s = 0