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Homework Help: Attraction and gravitational force.

  1. Oct 20, 2007 #1
    1. The problem statement, all variables and given/known data
    Two objects attract each other gravitationally with a force of 2.7 10-10 N when they are 0.25 m apart. Their total mass is 4.0 kg. Find their individual masses.
    larger mass - I kind of guessed this was 4.0 kg but don't know how to do it.
    smaller mass ? kg


    3. The attempt at a solution

    I don't quite understand how exactly this must be done. What formulas would i use?
     
  2. jcsd
  3. Oct 20, 2007 #2

    Doc Al

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    Staff: Mentor

    Use Newton's Law of Gravity. (No guessing allowed!)

    Call the masses M1 and M2, if you like.
     
  4. Oct 20, 2007 #3
    ahh.. i still dont get it???
     
  5. Oct 20, 2007 #4

    Doc Al

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    Staff: Mentor

  6. Oct 21, 2007 #5
    take two masses M1 and M2. problem says that M1+M2= 4.
    Newton's law of gravitation says that force between two objects of mass M1 and M2 is

    F = (gravitational constant) x (M1) x (M2) / (square of the distance)

    so u know F, gravitational constant, the value of distance. Substitute these values in the above equation, u gonna get a relation beween M1 and M2 something like ,
    M1= something times M2

    substiute that in M1 + M2 = 4,
    probably u get the answer.
     
  7. Oct 21, 2007 #6
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