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

[csgirl504]

Homework Statement

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

Homework Equations

k*|q1||q2| / r²

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!

 

[217 MeV]

Check your units for d! :)