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## Homework Statement

Three positive particles of charges +7.0 uC are located at the corners of an equilateral triangle of side 20 cm. Calculate the magnitude and direction of the net force on each particle.

Answer: 19.0 N [AWAY FROM THE CENTRE]

## Homework Equations

F = (kQ1Q2)/(r^2)

Where:

k is the Electrostatics Constant - 9 x 10^9 Nm^2/C^2

Q1 and Q2 are the charges in (C)

r is the separation in (m)

F is the Electrostatics Force in (N)

## The Attempt at a Solution

Er, so I calculated the force on one of them from another, see below:

F = (kQ1Q2)/(r^2)

= [(9 x 10^9 Nm^2/C^2)(7.0 X 10^-6 C)(7.0 X 10^-6 C)]/(.20m)^2

= 11.0 N

And that's where I'm stuck: I have absolutely no idea how I would even obtain a number close to 19.0 N!

What I do understand is the direction: by [AWAY FROM THE CENTRE] they mean that because they are all positive charges, they will all repel away from one another- right? Do correct me if I'm wrong.

I really do appreciate it!