# Homework Help: Point Charge Problem (Not in a straight line)

1. Sep 13, 2010

### Chandasouk

Point charge 2.0 uC is located at X= 0, X= 0.30m , point charge -2.0uC is located at X= 0 Y= -0.30m . What are (a)the magnitude and (b)direction of the total electric force that these charges exert on a third point charge Q= 5.0 uC at X= 0.40 , Y= 0?

I drew a diagram of what was going on and used Pythagorean theorem to find out that the distance between Q1 and Q is .50m as well as Q2 and Q. I then broke Q into its components and solved for (F1 on Q)x and (F1 on Q)y. But first

(F1 on Q) = (8.988*10^9)[(2*10^-60 * (5*10^-6)/(.50m)2] = 0.35952N

(F1 on Q)x= 0.35952N*cos$$\theta$$ = 0.35952N(.40/.50) = 0.287616N

(F1 on Q)Y= -0.35952N*sin$$\theta$$ = -0.35952N(.30/.50) = -0.215712N

Where do I go from here? And how do I find theta?

2. Sep 13, 2010

### Chandasouk

Okay, I got the force but how do I find the angle in degrees clockwise from the +x direction?