# Electric charge/Colombs law problems

1. Sep 9, 2011

### RandellK02

I have a problem im working on before the end of today and I am having some trouble getting the right answer. What am I missing?

1.
1. The problem statement, all variables and given/known data
The charges and coordinates of two charged particles held fixed in an xy plane are q1 = 3.11 μC, x1 = 5.72 cm, y1 = 0.703 cm and q2 = -6.23 μC, x2 = -1.59 cm, y2 = 2.45 cm. At what (a)x and (b)y coordinates should a third particle of charge q3 = 5.06 μC be placed such that the net electrostatic force on particle 2 due to particles 1 and 3 is zero?

2. Relevant equations
k=qQ/r^2

3. The attempt at a solution
q1=3.1 E-6 x:0.0572 m y:0.00703 m
q2=-6.23 E-6 x:-0.0159 y:0.0245 m
q3=5.06 E-6

First I find F1,2 for the x component:
F1,2x=kq1q2/d2
note:d=-0.0159 - 0.0572

Next I conclude for equilibrium @q2 q1x=q3x. Same for y component.

So to find X of q3...
F1,3x ==> F1,2x= kq1q3/x2

I assumed solving for X will give me the answer but its incorrect...
Similar process for the y component.

2. Sep 10, 2011