# physics

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A dockworker loading crates on a ship finds that a 20 kg crate, initially at rest on a horizontal surface, requires a 73 N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 50 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor. *PLEASE HELP*

• physics -

The crate's weight is M g = 196 N

That is the "normal force" on the surface below.

Mu-static = 73/196 = ___

Mu_kinetic = 50/196 = ___

Review the definitions of static and kinetic friction coefficients.

This is pretty basic stuff

• physics -

I try to looking for this answer but now I think I am a person should answer this question ^^. Ok

Sum F = ma ( because it get loading the crates )
Fp - F(fr) = ma
Fp = ma + F(fr)
Fp = ma + u(k) mg
=> u(k) = (Fp - ma) / mg ( with ma is 0 )
so u(k) = 59/ ( 22*9.8) ( because kenetic friction always moving )

The u(s) you guys can do the same thing , just replace another force number to the equation.