Coulomb's Law With Three Particles

1. Jan 30, 2005

I know how to use the law with two particles and sometimes with three, but the way this problem is set up has me a bit confused.

Use coulomb's law to find the electric force (magnitude and direction) on q for (a)q=2e-6 C and (b)q=-4e-6C.

The picture is this *sorry I have to actually draw it out*
(3e-6 C)--3cm---(q)---2cm--(4e-6C).

How do I use Coulomb's law to find the force on a particle IN BETWEEN two particles. Also does the fact that q changes from postive to negative (part a and then part b) affect this problem?

2. Jan 30, 2005

MathStudent

You can use the superposition of forces principle for coulombs law,
That is The net force acting on a particle is the (vector) sum of the forces from the other particles.
This means we can calcualte the force from each particle seperatly and then add these to get the net result ( I'm being very redundant :grumpy: )

Be careful to consider the directions of each force

come back and post your work if you need more help .

-MS