Field and force with three charges

[Squall]

Homework Statement

At a particular moment, three small charged balls, one negative and two positive,are located as shown in the figure. q1 = 3 nC, q2 = 7 nC, and q3 = -5 nC.

What is the electric field at the location of Q1, due to Q2?

y
q1
|
|
|
q2______q3____x

Okay that is the given diagram the if q2 is at (0,0) then q1 is at (0,4); q3 at (3,0);
and the distances are in centimeters

Homework Equations

I'm using Coulomb's Law which states that E = 9e9*(q/r^2)r-hat

The Attempt at a Solution

So I thought all I have to do is plug in the values

[9e9*(7e-9/(.004)^2)]*<0,4,0> = <0,3937500,0>N/C

please help me, I've been staring at this for a while and I cannot figure out why I don't get the right answer, I shouldn't have to consider the other charges because they don't affect the field created by q2 just the net field, so why is this not correct I have no idea.

Thanks Again for all the help guys

 

[ehild]

In what units are the components of the position?

ehild

 

[Squall]

The components of the positions are in centimeters. (cm)

 

[ehild]

If so, 4 cm = 0.04 m. And you have to use the unit vector in the direction of <0,4,0>.

ehild

 

[Squall]

Oh yes your right, I just kept converting the cm to m wrong, putting an extra zero in front of it like they were mm or something. Thank You so much it really helps having someone else look at this. I knew I had to be making some stupid mistake.