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Rotation of a non pivot object

  1. Sep 27, 2013 #1
    my teacher told.me.that If a rotating uniform stick is falling, the axis of rotation is about the cm of the stick.
    I dont understand why it is about the cm of the ball. I have searched on google and i found no answer.
    Can anyone give me some reference so that I can read? Can anyone explain to me? Thank you
  2. jcsd
  3. Sep 27, 2013 #2


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  4. Sep 27, 2013 #3
    i have read this note
    but i still cant the answer
    any tips?
  5. Sep 27, 2013 #4

    D H

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    You can describe the motion of a rigid body as a combination of translation of some point fixed with respect to the rigid body and rotation about that point. That point? It's completely arbitrary. It doesn't even have to be a point on the object. It's a consequence of Euler's rotation theorem.

    So why choose the center of mass? That is the one point for which translational and rotational motion decouple from one another.
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