# Potential energy of the system increase or decrease?

1. Oct 8, 2005

### brandon26

When two electrons move away from each other, does the potential energy of the system increase or decrease?

2. Oct 8, 2005

### Physics Monkey

What work have you done? What is the potential energy of two electrons separated by a certain distance?

3. Oct 8, 2005

### brandon26

No, this is a question where numerial values are given. I thought that the totla potential energy stays the same because they both move off in differnt directions

4. Oct 8, 2005

### Physics Monkey

I don't understand, what are you saying "no" to?

Why do you think this? Again let me ask, what is the potential energy of two electrons separated by a certain distance? How does it change with the distance?

5. Oct 9, 2005

### Dr.Brain

In this case the potential energy of the system is given by k(-e)(-e)/r where r is the distance between the axes. As the two electrons move away from each other , the 'r' increases and thus the P.E decreases , because the system will always prefer to have minimum PE , therefore two electrons SHOULD remain away from each other.That is why the two electrons repel each other.

BJ

6. Oct 9, 2005

### Tide

HINT: If the sum of the kinetic and potential energy is a constant and the kinetic energy increases what happens to the potential energy?