# Applications of Newton's Laws of Motion

1. Sep 25, 2008

### pstfleur

1. A toboggan slides down a hill and has a constant velocity. The angle of the hill is 8.00 with respect to the horizontal. What is the coefficient of kinetic friction between the surface of the hill and the toboggan

2. Static Frictional Force, FsMax=msFn

3. I have no freaking idea. All I have is an angle, and the information in the book doesn't give me enough information on the coefficient of kinetic friction. Please help

2. Sep 26, 2008

### Clairefucious

Hey, don't stress! All you need is the angle. The static coefficient of friction is a ratio of the component of the force along the slope and the component of the force normal to the slope. It is independent of mass of object and material of object and slope.

Consider the force trying to drag the toboggan down the hill. This is from acceleration due to gravity. The normal force (at 90 degrees to the slope) is going to be Fn = Fg cos(angle). The force along the slope is going to be Fs = Fg sin(angle). So when you calculate the static coefficient of friction you have

ms = Fs/Fn where you can substitute in the two formula for Fn and Fs I have written above.

3. Sep 26, 2008

### pstfleur

Thank you very much.. That really helped me understand the problem.
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