Downloading collisionlab 1.0.3 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. The program lies within Education Tools, more precisely Teaching Tools. This free software for Mac OS X was originally developed by Hassan Mallahzadeh. We recommend checking the downloaded files with any free antivirus.
From the developer:
collisionlab is designed to help you simulate collisions. It provides everyone who deals with collisions - specifically physicists and video game developers - a visually-appealing medium to test their knowledge. The application makes it possible to observe elastic and inelastic collisions and study their relation with conservation laws, not only in the lab frame but also in the center of mass frame.
You may want to check out more Mac applications, such as Collision Lab, which might be related to collisionlab.