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Homework Help: Rolling Without Slipping Down a Slope

  1. Apr 1, 2015 #1
    1. The problem statement, all variables and given/known data
    A hollow, spherical shell with mass 1.85kg rolls without slipping down a slope angled at 32.0∘. Find the acceleration, friction force, and coefficient of friction.

    2. Relevant equations
    atan= rα

    3. The attempt at a solution
    I'm not quite sure where to begin. I started by making a FBD and using Newton's Second Law to determine Fs-mgsinΘ=max. Since the shape is a hollow sphere, the moment of impulse is I=mr2. I know the frictional force is causing the torque. Without the height of the ramp or the radius of the shell, I'm not quite sure how the proceed, but once I can solve for the acceleration, I should be able to solve for the frictional force and coefficient of friction quickly. This seems like a simple problem, but I'm at a loss with regards to how to approach it.
  2. jcsd
  3. Apr 1, 2015 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Check that.
    Never be afraid to throw in symbols for such unknowns. Generally you will find they cancel out later.

    There's not enough information to find the coefficient of friction, but you can find a lower bound for it.
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