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Homework Help: 2D Motion Find speed.

  1. Nov 11, 2013 #1
    1. The problem statement, all variables and given/known data

    A 42.5kg person is going down a hill sloped at 42.0 degrees. The coefficient of kinetic friction between the snow and skis is 0.180. How fast is the skier going 4.56 seconds after starting from rest?

    2. Relevant equations

    Is ffkmax equal to net force?

    3. The attempt at a solution
    coefficient of kinetic friction:.180 t=4.56 mass=42.5kh Angle=42 degrees Vo=0

    I created a free body diagram.

    I used (mg)(cos 42) to get total force going opposite of FN. I made that force equal to FN and plugged the number into the equation ffkmax=coefficient(.180)*FN(315.83).

    Got 76.5N=ffkmax. Now im not sure if i use fnet=ma or a motion equation.
  2. jcsd
  3. Nov 11, 2013 #2


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    Science Advisor
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    Which way does the frictional force point, up or down the slope? If it were the only force in that direction, which way would the skier move?
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