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Homework Help: What is the kinetic friction coefficient?

  1. Jan 29, 2015 #1
    1. The problem statement, all variables and given/known data
    A skier is sliding down a 20o slope at constant speed, what is the kinetic friction coefficient?

    2. Relevant equations
    E = 1/2 mv2
    W = Fd
    F = ma
    F = μN = μmg

    3. The attempt at a solution
    Attempted to use ma = μmgsin20, which crosses out the masses since mass was not given, but the skier is going at a constant speed so I'm assuming acceleration would be zero. Though I'm not sure how to continue the question or if I'm on the right track. Thanks in advance!
  2. jcsd
  3. Jan 29, 2015 #2
    Have you tried drawing a force diagram? If not, start here. You'll notice that your expression for the force of friction is incorrect (the μmg part), and that you have left out a force along the slope (the component of a force to be more specific)

    You are correct that the acceleration would be zero.
  4. Jan 29, 2015 #3
    Ah, figured out what I was doing wrong, thank you! :)
  5. Jan 29, 2015 #4
    You're right, the acceleration is zero. But you are missing one force. Why don't draw an FBD of the skier on the incline.
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