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Kepler's third law

  1. Oct 16, 2005 #1
    Two gravitionally bound stars with equal masses m, separated by a distance d, revolve about their center of mass in circular orbits. Show that the period tau is proportional to d^1.5

    Could someone get me started on this? I have no idea where to begin!

  2. jcsd
  3. Oct 16, 2005 #2

    Chi Meson

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    First of all, state Keppler's Third Law.

    Also, realize that d^1.5 is the same as d^(3/2)

    And then notice how the radius of the orbits is directly proportional to the distance between them.
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