1. The problem statement, all variables and given/known data I want to know what happens to particles inside a material, when they are pulled or fixed. That's all I've been asked to do. 2. Relevant equations There are none. 3. The attempt at a solution I've been searching through google and ask.co.uk but everything I click on doesn't talk about particles. I've been asked to research through the internet and I feel this is the best place to come to.