# physics

if you use a horizontal force of 30 N to slide a 12 kg wooden crate across a floor at a constant velocity, what is the coefficient of kinetic friction between the crate and the floor?

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1. Wb = M*g = 12 * 9.8 = 117.6 N. = Normal
force, Fn.

Fx-Fk = M*a.
Fx-Fk = M*0 = 0.
Fk = Fx = 30 N.

Fk = u*Fn.
u = Fk/Fn = 30/117.6 = 0.255.

Note: Since the velocity is constant, the acceleration is zero.

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