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Homework Help: Angular momentum finding the principle axis

  1. May 24, 2010 #1
    If an object is rotating about the axis of symmetry
    and you are trying to find the angular momentum about the mass centre g.

    Does a rotation about the axis of symmetry correspond to a rotation about the principle axis?


    For this question i am trying to find the angular momentum about the mass centre of cone which is rotating about its axis of symmetry. However the axis of rotation is also rotating about the z axis.

    Does the angular velocity w effect the angular momentum about the mass centre? I am guessing it would...

    The only thing i am not sure about weather or not angular momentum about G would be evaluated about the principle axis
  2. jcsd
  3. May 24, 2010 #2


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    Hi SpartanG345! :smile:

    (btw, it's principal axis, like the principal of your school :wink:)
    Every axis of symmetry is a principal axis.

    The principal axes of a cone are its centre line, and every direction perpendicular to that line.

    To find the angular momentum, you must first find the angular velocity …

    if that is along a principal axis, then just multiply by the moment of inertia; if not, then use the tensor method. :wink:
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