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Cmertin

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## Homework Statement

A 75Kg skier starts down a 50m high 10˚ slope. What is his speed at the bottom?

Part A: Consider skis frictionless

Part B: Assume that the coefficient of kinetic friction between the skis and the surface of the slope is µ

_{k}=.05

## Homework Equations

|F

_{f}|=µ

_{k}•|F

_{N}|

F

_{net}=-F

_{f}+F

_{N}+F

_{g}=0=ma

a=g•sin(ø) (pretend that chi is theta)

F

_{N}=ma•cos(ø)

Values I figured out from Part A:

The length of the slope (on the hypotenuse) is 288m

Initial velocity in both the X and Y is 0m/s

For part A, the final velocity is 31m/s (does not need to be checked)

## The Attempt at a Solution

Part A:

I got part A with 31 m/s and I know it's right.

Part B:

0=F

_{net}=F

_{g}+F

_{N}-F

_{f}=ma (Newton's second law)

F

_{f}=F

_{g}+F

_{N}

F

_{N}=75Kg•9.81m/s

^{2}•cos(10˚)=724.6N

I think that I have to plug the normal force into the friction equation (|F

_{f}|=µ

_{k}•|F

_{N}|

) though I'm not sure if I have to and then I don't know what I would do after that.

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