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Homework Help: Dynamics of Uniform Circular Motion

  1. Jul 30, 2009 #1
    1. The problem statement, all variables and given/known data
    A suitcase is on a sloped carousel (slope = 36degrees) with a radius of 11m and a constant speed. The suitcase has not slid all the way down the carousel.The coefficient of static friction between the suitcase and the carousel is 0.76. How much time is required for the suitcase to go around once?

    2. Relevant equations
    velocity = 2 * (pi) * r / period of motion

    3. The attempt at a solution
    Not sure what to do here. 2 unknowns in the equation above. Does the angle even matter?
  2. jcsd
  3. Jul 30, 2009 #2


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    Staff Emeritus
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    Gold Member

    Indeed. The period is what you are trying to solve for. Knowing the radius of the circular path taken by the suitcase requires knowing exactly where on the carousel (how far down) the suitcase is sitting. This can be figured out by evaluating the conditions required to keep the suitcase in static equilibrium on the surface of the carousel. So, yes, the angle of slope does matter.

    EDIT: On second thought, that makes no sense. Static equilibrium just tells you that the suitcase will remain wherever it is. It doesn't tell you where it is in the first place.

    You can verify that the suitcase won't slide at all by comparing the coefficient of static friction to the coefficient of static friction that would be required in order to keep the suitcase in place at that slope. That's all the insight I have right now...
    Last edited: Jul 30, 2009
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