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Homework Help: Coulomb's Law and the moon

  1. Sep 10, 2007 #1
    1. The Moon and Earth are bound together by gravity. If, instead, the force of attraction were the result of each having a charge of the same magnitude but opposite in sign, find the quantity of charge that would have to be placed on each to produce the required force.

    2. Fe = ke |q1||q2|/r^2

    3. 9.81 = ke |x||-x|/r^2
    solving for x, I ended up getting -.64766

    Not sure if I understand the problem correctly or not. Please help steer in the right direction. Thanks
  2. jcsd
  3. Sep 10, 2007 #2


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    I think you need to equate the gravitational pull of the earth on the moon with [tex]F_e[/tex]. Since you know the radius from the center of the earth to the center of the moon, and you know [tex]k_e[/tex], you can find the two "q"s by a simple square root operation, making one positive and the other negative.
  4. Sep 10, 2007 #3
    I got it..thanks
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