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Rotating Object - zero KE

  1. Sep 6, 2013 #1

    Since velocity is a vector quantity I assume it follows that KE must also by a vector since KE=1/2mv squared.

    Is it true to say a rotating object has zero total velocity since + = - and therefore the total KE is zero?

  2. jcsd
  3. Sep 6, 2013 #2


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    Staff: Mentor

    No, because kinetic energy is not a vector quantity. It is a scalar. Think of the ##v^2## as coming from the vector dot product of the velocity with itself: ##v^2 = \vec v \cdot \vec v = v_x^2 + v_y^2 + v_z^2##.

    There is such a thing as rotational kinetic energy.

    Last edited: Sep 6, 2013
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