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Merry-go-round + sphere tied to rod

  1. Nov 10, 2009 #1
    1. The problem statement, all variables and given/known data

    A small 0.160 kg sphere is suspended by a light string from a vertical post mounted at the edge of a merry-go-round of radius R = 0.440 m.
    The equilibrium position of the sphere is shown in the figure, with a = 0.430 m and b = 0.760 m. The axis of rotation is indicated by the dashed line. Calculate the angular velocity of the merry-go-round.

    http://img694.imageshack.us/img694/2586/physicshelp.jpg [Broken]

    3. The attempt at a solution

    This is where I'm getting stuck. I can't figure out where to start. I have an idea that this problem deals with Newton's 2nd law, but I don't know how to apply it this situation.

    Would using the torque equation help?: [tex]\tau = F * r * sin\theta[/tex]
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 10, 2009 #2

    Doc Al

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    Staff: Mentor

    Follow standard procedure: Draw a free body diagram of the sphere, showing all the forces acting on it. (Hint: There are only two forces.) Key: What's the acceleration of the sphere? Then apply Newton's 2nd law.

    (No need for torques.)
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