- #1

BlackMamba

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I could use a little guidance on this problem.

An extreme skier, starting from rest, coasts down a mountain that makes an angle of 25 degrees with the horizontal. The coefficient of kinetic friction between her skis and the snow is 0.200. She coasts for a distance of 13.1m before comming to the edge of a cliff. Without slowing down, she skis off the cliff and lands downhill at a point whose vertical distance is 3.30m below the edge. How fast is she going just before she lands?

So here is my reasoning and what I have done thus far. I drew my free body diagram which really doesn't really do anything for me, but I know it is supposed to. Anyway, I also drew a little picture of what the hill and skier might look like.

I decided that to find the initial height I would use 13.1m(sin 25) to get the inital height. I know that the final height is 3.30m. I also know that initial velocity is 0 since she is starting from rest and I'm left to find the final velocity. So here's my little chart.

Ho = 5.54

Hf = 3.30

Vo = 0

Vf = ?

So forgetting about the friction for a moment I found the velocity the skier would be traveling at the landing point using this equation: Vf = square root of Vo^2 + 2g(Ho - Hf)

But I know that isn't the answer because I didn't take the friction into consideration. Thus my question. How do I fit that in there? This is the part that is stumping me. Perhaps I should have used a different equation to include the friction but I don't have the slightest clue what that could be.

Any help provided would be greatly appreciated.