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Homework Help: Sun's gravitational pull problem

  1. Dec 19, 2007 #1
    How far from Pluto must a space probe be along a line toward the Sun so that the Sun's gravitational pull on the probe balances Pluto's pull?

    I know that Fs=Fsp and that when i elminate terms i get ((Rsp-x)/x)^2=(Ms/Mp) i uncderstand the mass of pluto to be 1.3e22 kg and the mass of the sun to be 1.99e30 kg and the radius to be 5.91e15 m. I get 4.8e8 to be my answer in km. That is not correct however. Can you help me?
  2. jcsd
  3. Dec 19, 2007 #2


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    The force of gravity is F = G M m / r^2
    So simply set Msun / dsun^2 = Mpluto / dpluto^2, Cancelling G and the mass of you.
    Then you can work out a ratio between dsun and dpluto. You know dsun / dpluto so you can work out the position.
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