# Finding coefficient of kinetic friction

**1. The problem statement, all variables and given/known data**

A 100 N force directed 37° below the horizontal is applied to a 30 kg object on a horizontal surface. If the magnitude of the acceleration of the object is 1.3 m/s^{2}, what is the coefficient of kinetic friction (μk) between the object and the surface?

**2. Relevant equations**

F = ma

**3. The attempt at a solution**

I drew the body diagram and tried calculating the net force in the x direction.

This is what I got:

F = F_{px} (the 100 N force) – F_{fr}

F_{px} is 100cos37 and F_{fr} is μmg, so

ma = 79.86 – 294μ

I plugged in 1.3 for a and got 0.24 for the answer.

The correct answer is 0.12.

Not sure where I went wrong, any help would be appreciated. Thanks!

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