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Homework Help: Gravitationtrouble setting up equation

  1. Oct 1, 2007 #1
    My problem lies in setting this up.

    A particle of mass M is split into two pieces, M and M-m, and are set some distance apart.

    What ratio of m/M maximizes the magnitude of the gravitational attraction.

    I will definately be needing [tex] F_g=\frac{Gm_1m_2}{r^2}[/tex]

    I know that after making appropriate substitutions I get.

    but my problem is in how to compare what happens as m-->M?

    Any thoughts in the set up?

  2. jcsd
  3. Oct 1, 2007 #2


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    You mean that the pieces are m and M-m!!
    basically, you have to optimize the product m(M-m) as a function of m. Just take the derivative with respect to m and set the derivative equal to zero. That will give you the optimum m and then you may calculate the ratio m/M.
    Last edited: Oct 1, 2007
  4. Oct 1, 2007 #3
    AWWWW!! I knew that! I wrote out the product wrong! Thanks nrqed

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