In a game of pool the balls hit each other more times then in a Holyfield vs. Tyson match. These collisions are much more complex though. The key to billiards is to know what is going to happen to the balls after the collisions. This is important not only for making shots and pocketing balls, but also for setting up your next shot by placing the cue ball in line for the next ball. There are always ways of altering the spin of the ball to change where the ball will end up in, which we will discuss later in Torque.  In a head on collision, the object ball will continue on the path that the cue ball was on before the collision took place. In angular, two dimensional collisions, the two balls will always have a resulting angle of 90 degrees. A collision is also takes place when you strike the ball with the cue stick. This is called an impluse.

The Collisions in a game of pool can get very, very complex. For example, when you break, many of the balls are already moving at different speeds and different angles. These are difficult collisions to figure out, because you must use vectors. The velocity of the ball can be determined by using vectors. The formula for this can get very difficult. You must find the Velocity of the balls, with respect to the X axis, and then also the Y axis, to get a correct reading on the velocities. Then when you find those, you must add them together or subtract (if the balls are heading in opposite directions). You will eventually reach your final velocity.

Check out the Collision Applet owned by Mr. Michael Fowler. Thank you Mr. Fowler.