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neoncrazy101
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Homework Statement
A 71.2-kg skier coasts up a snow-covered hill that makes an angle of 31.4 ° with the horizontal. The initial speed of the skier is 9.96 m/s. After coasting a distance of 2.04 m up the slope, the speed of the skier is 4.41 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?
Homework Equations
Ef= Eo (aka 1/2mvf^2 + mghf = 1/2mvo^2 + mgho
The Attempt at a Solution
Final: 1/2(71.2)(4.41)2+71.2(-9.8)(1.74) = -521 (H=2.04cos(31.4), right?)
Initial: 1/2(71.2)(9.96)2+71(-9.8)(0) = 3531
The answer our phyrics program gives for this problem is A: -2100J and for B: 1030N. But I cannot figure this problem out. What am I doing wrong?