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Deriving Kepler's Third Law

  1. Oct 20, 2005 #1
    Two gravitaionally bound stars with equal masses m, separated by a distance d, revolve about their cneter of mass in circular orbites. Show that the period is proportional to d^3/2 and find the proportionality constant.

    I know that in this case, F = mv^2/r and that F=Gm^2/d^2.

    But where do I go from here??

    Thanks for any help!
  2. jcsd
  3. Oct 20, 2005 #2

    Andrew Mason

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    Equate the two forces (since centripetal force is supplied by gravity) and see what you get. (Note: r = d = distance between centres of mass).

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