[b]Ejs Hard Disk Gas model was created using the Easy Java Simulations (Ejs) modeling tool.  
It is distributed as a ready-to-run (compiled) Java archive.  
Double clicking the ejs_newton_HardDiskGas.jar file will run the program if Java is installed.  
Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.
Additional Ejs models for Newtonian mechanics are available.
They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.[/b]