# Homework Help: Principles of Potential Energy in a Multiparticle System

1. Oct 4, 2011

### Discovery09

Hello

The question is, which of these statements are true?

1) If released from rest two protons would move closer together, increasing the potential energy of the system.

- I determined that this would not be true considering they have they same charge, hence they would not attract but repulse each other. Therefore, they would not move closer together.

2) In some situations charged particles released from rest would move in a direction that increases electric potential energy, but not in other situations.

- I thought this was true due to the fact sometimes protons repel and hence decrease potential energy and electrons attract hence increasing potential energy.

3) If any two charged particles are released from rest, they will spontaneously move in the direction in which the potential energy of the system will be decreased.

- Given what I said in 1 regarding protons this wouldn't be true either.

This was my answer, but I was told that it's wrong does anyone know where I went wrong, or perhaps you do not see anything wrong with the reasoning I presented?

Last edited: Oct 4, 2011
2. Oct 5, 2011

### Spinnor

For your problems you can use T + V = constant, the kinetic energy plus the potential energy = constant.

For part 2, initially you have T + V = 0 + V = constant, and latter you are told you have both T and V getting larger. That can't happen, if one gets bigger the other must get smaller.

For part 3, initially you have T + V = 0 + V = constant, and latter you are told you have T gets bigger and V gets smaller, that can happen, if one gets bigger the other must get smaller.