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Homework Help: Rotational motion energy

  1. Dec 16, 2014 #1
    1. The problem statement, all variables and given/known data
    Same mass sphere and cylinder are rolling on a horizontal plane. Which part of each objects kinetic energy does objects rotational energy make up?

    2. Relevant equations
    Erotational = 1/2 Iw2

    Ekinetic = 1/2 mv2

    3. The attempt at a solution

    I know, that moments of inertia are:

    Icylinder = 1/2 MR2

    Isphere = 2/5 MR2

    And I know that:

    Etotal = Ek + Erotational

    What sould I do?

    Last edited by a moderator: Dec 16, 2014
  2. jcsd
  3. Dec 16, 2014 #2

    Doc Al

    User Avatar

    Staff: Mentor

    For rolling without slipping, how are ##\omega## and ##v## related?
  4. Dec 16, 2014 #3
    Well, v = wR .
  5. Dec 16, 2014 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Exactly. Use that to relate rotational and translational kinetic energy.
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