# Collision of a sphere into a cluster of spheres (billiard balls)

1. Jun 10, 2013

Hello all,

I am attempting to simulate collisions of pool balls. For the moment i am doing so without taking rotational momentum or friction between balls into account. right now i have a system that successfully simulates a collision between 1 ball and another ball. Here's how it basically works:

(assuming object ball is stationary)

The object ball basically gets or absorbs the white ball's velocity component along the x axis (the axis axis being the line passing through the centers of both balls) while the white ball retains the y component of its original velocity. therefore in my simulation a straight shot (or a full ball shot) would make the while ball stop and the obj ball absorbs all its velocity. Ofc my simulation also works for arbitrary velocities for any number of balls.

The problem i am having is i cant figure out what happens when the while ball collides into a cluster of balls(e.g break shot). I know that in real life the white ball basically bounces back. i am guessing this is due to the cluster having a larger mass collectively. In my algorithm, increasing the mass of one of the balls does generate that 'bounce back' effect. However when dealing with a cluster, how do i know by how much to increase the mass for each collision, both between the white ball and the cluster, and the other internal collisions that happen whithin the cluster. Can anyone help?

Thank you

2. Jun 10, 2013

### Staff: Mentor

You can split the collision into many collisions between the individual balls. Add some randomness in the precise ball positions, and this could give a realistic simulation.

3. Jun 14, 2013