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The shape of spinning liquid

  1. Feb 4, 2005 #1
    One simple question: why do liquid mirrors assume a parabolic shape when subject to uniform angular motion? (I mean, why not circular, or some other reasonably curved shape?)
    Last edited by a moderator: Feb 4, 2005
  2. jcsd
  3. Feb 4, 2005 #2


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    Think in terms of the definition of a parabola - the path followed by a plot of points equidistant from a point and a plane. You have two forces in play with a spinning liquid, gravity and centrifugal force. Centrifugal force pushes the liquid along the x - axis, gravity attracts the liquid along the y - axis. The centrifugal force component increases with the square of the distance from the center whereas the gravitational force component remains constant.
  4. Feb 4, 2005 #3
    Wow, that makes so much sense! Thanks a lot Chronos. :smile:
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