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Homework Help: Angular momentum of merry go round turntable

  1. May 12, 2008 #1
    Hi, I got this question wrong on a test and am really quite lost about it. I'd appreciate somebody running me through it.


    "Suppose a 55 kg person stands at the edge of a 6.5 m diameter merry go round turntable that is mounted on a frictionless bearing and has a moment of inertia of 1700 kg m^2. The turntable is at rest initially, but when the person begins running at a speed of 3.8 m/s (with respect to the turntable) around its edge, the turntable begins to rotate in the opposite direction. Caculate the angular velocity of the table."


    So I set up conservation of angular momentum
    L_f = L_i
    (Iw)_f = (Iw)_i

    Can somebody please help me from there?
  2. jcsd
  3. May 12, 2008 #2
    I guess you'd treat the person as a point mass, so the person has moment of inertia mr^2. Can you calculate his angular velocity?
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