Hi all, I'm trying to write a simple java applet that shows perfectly elastic billiard balls bouncing round a table, and bouncing off each other. I'm describing each ball's velocity with u and v component speeds at right angles, along and across the table. What I'm after is a clean and simple way of finding the u and v components of two balls' velocities after they collide, given that neither ball is likely to be at rest before the collision. Explanations I've found online all describe each ball's velocity in terms of a speed and an angle, and always with one ball a rest. When I try to work through the problem the way I want to (with u and v vectors) I get in a mess and haven't yet managed to produce results that look realistic. I'd be grateful for any help. kat.