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Homework Help: Coulomb's Law Question grade 12

  1. Apr 9, 2012 #1
    1. The problem statement, all variables and given/known data

    Three point charges, q₁= -5.00 μC, q₂= -4.00 μC, and q₃ which is negative are arranged as shown on three corner of side a=0.500 m. The direction of the forces on q₁ is at +20.0° with respect to the + x axis. Calculate the magnitude of q₃. The diagram looks something like this:
    ---------(-) q2
    | (square) |
    | (square) |
    | (square) |
    (+)------(-) q3

    2. Relevant equations

    F = kq1q2
    3. The attempt at a solution
    I used the above formula and I put q3 as a variable. I found the two forces, the first one which is what q1 exerts on q3 and the second which is what q2 exerts on q3:

    F(1 on 3) = 1.69 X 10^5 x (q3)
    F (2 on 3) = 1.44 x 10^5 x (q3)

    But then I'm stuck...
  2. jcsd
  3. Apr 9, 2012 #2
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