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Homework Help: Constant speed and friction (please help)

  1. Jul 4, 2007 #1
    Okay, here's the question:

    A box full of physics books (31 kg) is pushed across the floor at a constant speed by a force of F = 85 N at an angle theta = -40 degrees. Determine the coefficient of kinetic friction between the box and floor.

    My question is (for later calculation) if the box is moving at constant speed, does the F = 85N really matter?
  2. jcsd
  3. Jul 4, 2007 #2


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    Staff: Mentor

    Absolutely - that force (the horizontal component....) is what opposes the friction to keep the speed constant.
  4. Jul 5, 2007 #3

    Doc Al

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    Staff: Mentor

    That force also affects the normal force, which you'll need to figure out to calculate the coefficient of kinetic friction.
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