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Merry go round

  1. Jan 12, 2012 #1
    Imagine I stand on a merry-go-round and throw a ball inwards towards the center. The path will make a curve due to the coriolis force. I want to know what explains this.
    If the ball is thrown inwards, the velocity of the disk gets slower and slower the lower radius as seen from our frame of reference. This will make the ball faster than the rotation.
    But at the same time, the balls angular momentum should also be conserved, and thus that should also make the velocity greater. Do both these things then contribute to the coriolis force?
  2. jcsd
  3. Jan 12, 2012 #2


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    Staff: Mentor

    I thought the path merely appears curved because the merry go round is spinning. Isn't it going in a straight line?
  4. Jan 12, 2012 #3
    Not if you see it from the merry-go-rounds point of view. If you are looking from an inertial frame yes. Thats how I think it is.
  5. Jan 12, 2012 #4
    If you're in the rotating frame and want to explain the weird curved path taken by the ball as you see it, you have to invoke the inertial forces, i.e Coriolis and centrifugal forces. But if you do that and calculate where the ball should go while under the influence of those forces, you should predict the trajectory correctly, in reference to your rotating coordinates.

    It just so happens that in the external stationary frame, the calculation is much easier to do, and the trajectory is relatively trivial. If you really want to do it in the rotating frame, however, you can.
  6. Jan 13, 2012 #5
    Who say that angular momentum should be conserved in a non inertial frame of reference?
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