# Collisions

Jim Hurley jhurley0305 at sbcglobal.net
Mon Mar 26 18:15:37 EDT 2012

```Richard,

That 9 ball stack is a bit wonkish.

I have extracted from that stack the basic elements that illustrate the collision process. It can be found in:

go url "http://jamesphurley.com/jhurleyFolder/TwoBallCollisions.livecode"

It illustrates the physics of the ideal collision. The momenta along the line of the collision (the line joining  the two centers of the balls) is exchanged in the collision, while the momenta (velocities) perpendicular to this line are unaffected in the collission. That is the very definition of an ideal elastic impact.

But you needn't  worry about all that, just  use the "newVel" function to generate the after collision velocities given the before collision velocities.

Jim

>
> Message: 10
> Date: Sun, 25 Mar 2012 15:23:13 -0400
> From: Richard MacLemale <richard at richardmac.com>
> To: How to use LiveCode <use-livecode at lists.runrev.com>
> Subject: Re: Collisions
> Content-Type: text/plain; charset=us-ascii
>
> Jim,
>
> Thanks for taking the time to respond with such great explanations!  Of course, since I spent most of my time in high school math staring at a girl named Lisa, it's a bit challenging for me.  I downloaded the 9 ball example and plan on spending a lot of time learning how it works.  Thanks for sharing your knowledge - I really appreciate it.
>
> ---
> Richard MacLemale
> Music = http://www.richardmac.com
> Programming = http://www.macandchee.se
>

```