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Homework Help: Distance between charges.

  1. Jan 8, 2008 #1
    1. The problem statement, all variables and given/known data

    Two charges attract each other with a force of 3.0 N. What will be the force if the distance between them is reduced to one-ninth of its original value?

    2. Relevant equations

    (rA/rB)^2

    3. The attempt at a solution

    not sure how to find this.
     
  2. jcsd
  3. Jan 9, 2008 #2

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    What is rA and rB?
     
  4. Jan 9, 2008 #3
    sorry was a formula, i figured it out though,

    (rA/rA9)^2 = 81

    81* 3.0 N. = 243 N

    Okay so i got the answer, maybe someone could explain what is going on if you will?
     
  5. Jan 9, 2008 #4

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    Use Coulomb's law directly. Take the charges to be q1 and q2, and the initial dist between them to be r.
     
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