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Homework Help: Coulomb's law problem

  1. Jun 20, 2014 #1
    1. The problem statement, all variables and given/known data

    Two small spheres of charge 10Q each separated by a distance d repel each other with a force F. In terms of F what would be the new repulsive force if 2Q were removed from one sphere and added to the other?

    2. Relevant equations

    F = kQq/r^2

    3. The attempt at a solution

    F = k(10Q)(10Q)/d^2 if 2Q were removed.... F = k(12Q)(8Q)/d^2

    Is that the answer? it seems too easy

    Thanks for any input!
  2. jcsd
  3. Jun 20, 2014 #2
    You need to find what fraction of F is the new force. Just one more step to do.
  4. Jun 22, 2014 #3
    Your answer is correct but is not "In terms of F". Tip do not use the same symbol "F" to represent two different quantities. If the original force is F than the new force could be any of f, F', F2, or even G. But it is not F. F is already taken.
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