college physics
posted by ann .
A man pushing a crate of mass m = 92.0 kg at a speed of v = 0.860 m/s encounters a rough horizontal surface of length = 0.65 m as in the figure below. If the coefficient of kinetic friction between the crate and rough surface is 0.355 and he exerts a constant horizontal force of 300 N on the crate, find the following.
Find the magnitude and direction of the net force on the crate while it is on the rough surface.

The net force in the "rough patch" is the pushing force minus the kinetic friction force.
Fnet = 300  M*g*0.355 = 20 N
The crate will decelerate at a rate
a = Fnet/M = 3.38 m/s^2
It will continue moving for a time
t = Vo/a = 0.254 seconds, at which time it will stop after traveling 0.11 meters
The applied force will not be enough to move it farther.