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Homework Help: Gravity and mass of two objects

  1. Jun 4, 2008 #1
    1. The problem statement, all variables and given/known data
    There are two masses of unknown weight on a straight line with a small red particle between them. At x (Measured from the center of m1) = .515 the particle does not move. What is the ratio of the two masses? i.e. m2/m1.

    2. Relevant equations

    3. The attempt at a solution

    So do I use F = G*m1*m2/r^2? Since the particle isn't moving then the forces are balanced does this mean F = 0 then?
  2. jcsd
  3. Jun 4, 2008 #2


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    Hi AnkhUNC! :smile:
    Not exactly … you use F1 = G*m*m1/r1^2 and F2 = G*m*m2/r2^2 and F1 = F2.

    Hint: what is the relationship between m1/m2 and r1/r2? :smile:
  4. Jun 4, 2008 #3
    On the right side the min x = .043 on the left side the max is .957. It starts out at .5 though which is in the middle so I guess <- is 0 and -> is 1.

    r1/r2 = 1, they're both .5 away so .5/.5 = 1.

    m2 is greater than m1 because the attraction is stronger so does m2 = .515 and m1 = .485?
  5. Jun 4, 2008 #4
    So F = G*m*m1*m2?
  6. Jun 5, 2008 #5


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    Sorry, AnkhUNC, but I honestly have no idea what this means. :confused: :cry:
    Hint: divide F1 by F2. :smile:
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