Here is the problem: A 12.5 Kg wooden crate with an initial velocity of 2.5m/s slides across a rough cement floor for 1.7 m before coming to rest. Find the coefficient of kinetic friction. (Use GUESS method.) The answer is 0.19. The equation you use is: coefficient = kinetic friction/normal force I worked backwards so I got 0.19 = kinetic friction/(9.8 gravity x 12.5 kg) That means the kinetic friction has to be 23.275 N. Can someone show me how to work this one correctly. I don't know where the 23.275 came from.