# What is the electric force acting on the charge at the origin?

1. Consider three charges q1 = 4.3 nC, q2 = 6.6 nC, and q3 = -2.3 nC, arranged in a triangle as shown below.

(a) What is the electric force acting on the charge at the origin?
N, ° counterclockwise from the negative x-axis

(b) What is the net electric field at the position of the charge at the origin?
N/C, ° counterclockwise from the negative x-axi
picture of problem
http://www.webassign.net/holtphys/p16-38alt.gif

2. Homework Equations
F=kQ1Q2/r^2

3. The Attempt at a Solution
a) What is the electric force acting on the charge at the origin?
1.1739e-5 N, 270 ° counterclockwise from the negative x-axis

(b) What is the net electric field at the position of the charge at the origin?
4.3e12 N/C, 270 ° counterclockwise from the negative x-axis

## The Attempt at a Solution

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Simon Bridge
Homework Helper

The procedure is to work out the force vectors for each charge and add them.
(Hint: pythagoras)

270 degrees looks a bit odd to me. That would be pointing along the +y axis.
reality-check: q1 is repulsed by q2 and attracted to q3 so the force points down and to the right ... so the angle should be less than 90 degrees.

Your equations are more carefully written like this:
$$\vec{F}_{a,b}=\frac{kq_aq_b}{r_{b,a}^2}\hat{r}_{b,a}\qquad \vec{F}=q\vec{E}$$

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