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**2D Friction--Finding the Force of Friction without Mu**

## Homework Statement

A 1500kg car is parked on a 4-degree incline. The acceleration of gravity is 9.8 m/s

^{2}. Find the force of friction keeping the car from sliding down the incline.

## Homework Equations

F

_{W}=mg

[Sigma]F

_{y}=0, so Top=Bottom

"Friction is Fun:" f

_{s}=mu

_{s}F

_{N}

Since the degree of incline is 4 degrees, the angle with the "left" part of the x-axis on the free-body diagram and F

_{W}is 86 degrees.

## The Attempt at a Solution

After drawing a free-body diagram, I calculated F

_{w}=(1500)(9.8)=14700N

Next, I used Top=Bottom to calculate F

_{N}=14700sin(86)=14664.19154N

Third, f

_{s}=mu

_{s}F

_{N}. This is where I got stuck. How can I solve for the force of friction without mu?