# Introduction to Electrostatics -- Positive charges at the corners of a triangle

• molakko
In summary, the problem involves three positive particles of charges 11 μC located at the corners of an equilateral triangle of side 15.0 cm. The task is to calculate the magnitude and direction of the net force on each particle using Coulomb's Law. After discussing the symmetry of the problem, it is determined that the net force on each particle can be found by calculating the force of one particle on the other two and adding them together. After some calculations, the net force on each particle is found to be 84 N.
molakko

## Homework Statement

Three positive particles of charges 11 μC are located at the corners of an equilateral triangle of side 15.0 cm. Calculate the magnitude and direction of the net force on each particle.

Coulomb's Law

## The Attempt at a Solution

I think, that this is easy task, but I really don't know how to solve this. Please help me guys :P

Hi molakko, Welcome to Physics Forums.

You must make some attempt to show what you've tried or at least what you know about the problem before any help can be given. Pick one of the charges and describe the forces acting on it.

gneill said:
Hi molakko, Welcome to Physics Forums.

You must make some attempt to show what you've tried or at least what you know about the problem before any help can be given. Pick one of the charges and describe the forces acting on it.
For every charge 2 forces are acting. They are equal and they are same for every charge, becuase charges are the corners of equilateral triangle and charges have the same value, so we have to calculate magnitude and direction of the net force only for one particle to solve this task.

Correct. So what is it that stops you from doing that ? You have found one symmetry that reduces the work by a factor of three.
Pick one of the three particles and calculate the net force on it !

BvU said:
Correct. So what is it that stops you from doing that ? You have found one symmetry that reduces the work by a factor of three.
Pick one of the three particles and calculate the net force on it !

I really don't know how to solve that... just help me, please. I need this solution.

Coulombs law gives magnitude and direction for the force of particle 1 on 3 and for the force of particle 2 on 3. Add the two vectors and presto !

Is that true that magnitude of the force for two particles is equal to 48.4 N, hence magnitude of net force for each particle is equal to 83.831 N? (Assuming that Coulombs const is equal to 9*109)

Last edited:
molakko said:
Is that true that magnitude of the force for two particles is equal to 48.4 N, hence magnitude of net force for each particle is equal to 83.831 N? (Assuming that Coulombs const is equal to 9*109)

No, you need to add the force vectors. Do you know how to do that? Can you post a sketch of the problem showing the force vectors?

No -- at least, I get something else. How did you calculate that ?
berkeman said:
No, you need to add the force vectors. Do you know how to do that? Can you post a sketch of the problem showing the force vectors?
Small glitch from our good spirit.

molakko: yes, well done. ##{q^2\over 4\pi\epsilon_0r^2} =48.4\ N\ \ ## and ## \ 2\;48.4\;{\tfrac 1 2}\sqrt 3 = 84 \ N##

Oops, thanks BvU!

## 1. What is electrostatics?

Electrostatics is the branch of physics that studies the behavior of stationary electric charges and their interactions.

## 2. What is the significance of positive charges at the corners of a triangle in electrostatics?

In electrostatics, positive charges at the corners of a triangle represent an example of a stable equilibrium configuration. This means that the system will remain in this state unless acted upon by an external force.

## 3. How do positive charges interact with each other in electrostatics?

Positive charges interact with each other through the electrostatic force, also known as the Coulomb force. This force is attractive for opposite charges and repulsive for like charges, and it follows an inverse square law.

## 4. Can positive charges be created or destroyed in electrostatics?

In electrostatics, charge is conserved, meaning that it cannot be created or destroyed. Positive charges can only be transferred from one object to another or redistributed within a system.

## 5. How is electrostatics related to other branches of physics?

Electrostatics is closely related to other branches of physics, such as electrodynamics, which studies the behavior of moving charges, and electromagnetism, which deals with the interactions between electric and magnetic fields.

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