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Homework Help: Electrostatic and Gravitational Forces

  1. Jun 5, 2007 #1
    *Thanks for the help*
     
    Last edited: Jun 6, 2007
  2. jcsd
  3. Jun 5, 2007 #2

    Doc Al

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    Staff: Mentor

    Hint: Call the distance "D". Maybe you don't need the actual distance. :wink:

    That's the one.
    No, that's the weight of the particles--their attraction to the earth, not to each other.
     
  4. Jun 5, 2007 #3
    *thanks for the help*
     
    Last edited: Jun 6, 2007
  5. Jun 5, 2007 #4

    Doc Al

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    Just set Fel = Fgrav.
    Get rid of that minus sign--you are comparing magnitudes.

    You are almost there. Clean up the q & Q, m & M stuff: the charges are equal; the masses are equal (and given). Solve for the charge then plug in the numbers.
     
  6. Jun 5, 2007 #5
    *thanks for the help*
     
    Last edited: Jun 6, 2007
  7. Jun 5, 2007 #6

    Doc Al

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    Looks good to me.
     
  8. Jun 5, 2007 #7
    Many thanks for your help.... All I often need is a prod in the right direction
     
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