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Conservation of Angular Momentum of solid sphere

  1. Oct 26, 2009 #1
    1. The problem statement, all variables and given/known data
    A small solid sphere, with radius 0.25 cm and mass 0.61 g rolls without slipping on the inside of a large fixed hemisphere with radius 17 cm and a vertical axis of symmetry. The sphere starts at the top from rest.

    And I figured out that the KE at the bottom is = .001J

    2. Relevant equations
    I really don't know what equations would be relevant besides a proportion..

    3. The attempt at a solution
    I'm thinking it's something like

    (#/.001) = (x/100)
    and I cross multiply to find x
    but I really have no clue and would really appreciate some help on this one!
  2. jcsd
  3. Oct 26, 2009 #2


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    What exactly do you want to find?
  4. Oct 26, 2009 #3
    The fraction of its kinetic energy at the bottom is associated with rotation about an axis through its center of mass
  5. Oct 26, 2009 #4


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    How did you get the kinetic energy at the bottom?
  6. Oct 26, 2009 #5
    by multiplying mgh = (6.1e-4)(9.8)(.17) = .001J
  7. Oct 26, 2009 #6


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    Then you are measuring potential energy relative to a plane passing through the radius of the hemisphere (taken as 0 potential energy).

    In that case, the potential energy at the bottom is mgh = (6.1e-4)(9.8)(-0.17) = -0.001 J

    Ok, so at the top, what energy does it have?

    At the bottom what types of energy does the sphere possess?
  8. Oct 26, 2009 #7
    Ok, so at the top it would be 0?
    At the bottom it would be all PE again
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