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Homework Help: Moment of inertia question

  1. Oct 5, 2009 #1
    1. The problem statement, all variables and given/known data

    In the experiment, you will study an oscillator called a "torsion pendulum."
    In this case, the restoring "force" is the torsion constant of the wire that
    suspends the weight X and the inertial term is the rotational inertia of the
    suspended mass. You will compare the periods of a suspended sphere and of a
    suspended cube. The rotational inertia of a sphere is Is = 1/10M_sD^2 where
    ms is the mass of the sphere and D is its diameter. The rotational inertia
    of a cube is Ic = 1/6m_S^2 where mc is the mass of the cube and S is the
    length of its side. If the cube and the sphere are suspended from the same
    wire, what is the expected ratio of their periods, Tc/Ts?
    Assume that D = S
    ms = 0.20kg
    and mc = 0.9 kg

    2. Relevant equations

    T=1/f, omega = 2pi*f

    3. The attempt at a solution

    so for this one I know that I can get the moment of inertia and get the
    angular frequency but I don't know what the restoring force constant k is.
    is that constant require or would it cancel out later on?
  2. jcsd
  3. Oct 6, 2009 #2
  4. Oct 6, 2009 #3


    User Avatar
    Homework Helper

    First work it out symbolically.
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