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Changing axis of a rotating wheel

  1. Mar 3, 2008 #1
    1. The problem statement, all variables and given/known data
    Imagine a woman standing on a rotating disc (D) with a rotating wheel in her stretched arms (se picture here: http://image.vandrermodlyset.net/rotation.jpg [Broken]). The wheel is oriented in a horizontal plane, with the rotating axis (W) of the wheel parallel to that of the rotating woman (O) – that is vertical. This situation is rather stable as long as the woman doesn’t get nausea or tired arms. In situation A: W = O = D.
    Lets say that she would suddenly change the axis of the rotating wheel (W) so that it became horizontal (situation B), and the wheel would now be oriented in the vertical plane intersecting the axis of the woman (O and D). A point on the outer rim of the wheel would form a helix-shape as the woman rotates on the disk.
    I know that this task (going from situation A to B) will be difficult, even more when the wheel rotates fast, but how can I prove this using equations from rotational dynamics.

    2. Relevant equations
    T (torque) = r X F
    L (angular momentum) = r x p

    3. The attempt at a solution
    The torque of the rotating woman rotates vetor L of the wheel until it becomes parallel to W=O=D
    Last edited by a moderator: May 3, 2017
  2. jcsd
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