# Magnitude and direction of the Electrostatic Force

## Homework Statement

3 identical charges of 2.0 uC are placed on the x-axis. The first charge is at the origin, the second to the right at x = 50cm, and the third is at the 100 cm mark. What are the magnitude and direction of the electrostatic force which acts on the charge at the origin?

F = k Q1Q2/r^2

## The Attempt at a Solution

F12 = (9.0e9 * 2.0e-6 * 2.0e-6) / 1m^2 = .036N

F13 = (9.0e9 * 2.oe-6 * 2.0e-6) / 0.5m^2 = .144 N

Magnitude = .036 + .144 = .18 N

Direction = I have no clue. If they are all identical wouldn't they all repel each? Wouldn't that make the overall direction to the left since each charge repels the charge at the origin.

Thanks for the help!

Last edited:

gneill
Mentor

## Homework Statement

3 identical charges of 2.0 uC are placed on the x-axis. The first charge is at the origin, the second to the right at x = 50cm, and the third is at the 100 cm mark. What are the magnitude and direction of the electrostatic force which acts on the charge at the origin?

F = k Q1Q2/r^2

## The Attempt at a Solution

F12 = (9.0e9 * 2.0e-6 * 2.0e-6) / 1m^2 = .036N

F13 = (9.0e9 * 2.oe-6 * 2.0e-6) / 0.5m^2 = .144 N

Magnitude = .036 + .144 = .18 N

Direction = I have no clue. If they are all identical wouldn't they all repel each? What would that say about the direction?

Thanks for the help!

Hi wrenegade, welcome to Physics Forums.

If they all repel each other, in what direction is the charge at the origin going to want to move? What then is the direction of the net force on it?

Hi wrenegade, welcome to Physics Forums.

If they all repel each other, in what direction is the charge at the origin going to want to move? What then is the direction of the net force on it?

The charge on the origin would want to move left, correct? Making left the overall direction of the net force.

gneill
Mentor
The charge on the origin would want to move left, correct? Making left the overall direction of the net force.

Sounds good Sounds good Thank you very much!