Posted by Kelsey on .
A 220 N crate is pushed along the ground with a horizontal force. The coefficient of kinetic friction is 0.21 and the coefficient of static friction is 0.31. The crate moves at a constant speed of 4.1 m/s.
a) Draw a freebody diagram for the crate.
b) What is the size of the pushing force? 46.2 N
c) How long will it take the box to stop if the pushing force is removed?

physics 
Henry,
Fc = 220N @ 0deg. = Force of crate.
Fp = 220sin(0) = 0 = Force parallel to
ground.
Fv = 220cos(0) = 220N. = Force perpendicular to ground.
Fs = u*Fv = 0.31 * 220 = 68.2N. = Force
of static friction.
Fk = 0.21 * 220 = 46.2N. = Force of kinetic friction.
b. Fn = Fap  Fp  Fk = ma = 0, a = 0.
Fap  0  46.2 = 0,
Fap=46.2N.=Force applied(pushing force)