A 24-N Horizontal Force Is Applied to a 40-N Block $\mu$

Multiple Choice

A 24-N horizontal force is applied to a 40-N block initially at rest on a rough horizontal surface. Ifthe coefficients of friction are $\mu$ _s = 0.5 and $\mu$ _k = 0.4, the magnitude of the frictional force on the block is:

A) 8 N
B) 12 N
C) 16 N
D) 20 N
E) 400 N