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Homework Help: Combined rotational and translational motion

  1. Sep 11, 2009 #1
    1. The problem statement, all variables and given/known data

    I need to determine the total kinetic energy of a long thin rod relative to a laboratory frame which rotates around an axis at an angular velocity w and the axis moves at a constant translational velocity. The mass of the rod is M and the length of the rod is L. The translational velocity of the axis is Vaxis.

    2. Relevant equations
    Moment of Inertia, I, of rod is: 1/3 M (L sq) (This is because the rod rotates at one end).

    3. The attempt at a solution
    I believe the total kinetic energy should be: Total KE = 1/2 M (Vaxis sq) + 1/2 I (w sq).
    Is this correct?
  2. jcsd
  3. Sep 16, 2009 #2
    Hello e2m2a
    The moment of inertia is correct and addition of energies too. Is there some relation of the tangential and the rotational velocities. Remind that the endpoint velocitie for a whip is one mach. The maximum is there when the endpoint of the rods velocity L*w adds up to Vaxis.
    greetings Janm
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