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Homework Help: Coulomb's Law (Finding magnitude & direction of net force)

  1. Jan 25, 2012 #1
    1. The problem statement, all variables and given/known data

    Three positive particles of equal charge, +11.5 µC, are located at the corners of an equilateral triangle of side d = 13.0 cm (Fig. 16-50).

    Calculate the magnitude and direction of the net force on each particle.

    Image is here: http://www.webassign.net/giancoli5/16-38alt.gif

    2. Relevant equations

    k*|q1||q2| / r2

    3. The attempt at a solution

    Solving for net force on Q1:
    Ok, I drew a free body diagram. The force from q2 goes up and to right, q3 goes up and to left. I thought that since the x values will be the same due to symmetry, I could cancel them out and solve for the y value.

    So, I can find one force and multiply by two since they will be the same.

    I did 2 * { (9e9 * 11.5e-6 * 11.5e-6)/132 } * sin60

    I multiplied by sin60 to get the y value.

    My answer is coming out to be .0122, which is wrong. I'm not sure what I'm doing wrong. Can someone please explain? Thanks!
  2. jcsd
  3. Jan 26, 2012 #2
    Check your units for d! :)
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