Question

A force of 300N is sufficient to keep a 100_kg wooden crate moving at constant velocity across a wooden floor. what is the coefficient of kinetic friction?

Answer 1

300 = mu m g = mu * 100 * 9.81
That is it. Try yourself now.

Answer 2

M*g = 100 * 9.8 = 980 N. = Wt. of crate = Normal (Fn),
Fk = u*Fn = u * 100 = 100u = Force of kinetic friction,
F - Fk = M*a,
300 - 100u = 100*0 = 0,,
u = 3.