Computer Program Detail Page

Item Picture
Ejs Hard Disk Gas Model
written by Wolfgang Christian
The Ejs Hard Disk Gas model displays a two-dimensional gas made out of hard disks.  Particles are initialized with a speed v=1 in a random direction and move with constant velocity until a collision occurs.  You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.  

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 statistical mechanics are available.  They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Please note that this resource requires at least version 1.5 of Java (JRE).
Subjects Levels Resource Types
Classical Mechanics
- Linear Momentum
= Collisions in Two Dimensions
Thermo & Stat Mech
- Models
= Ideal Gas
- Lower Undergraduate
- Upper Undergraduate
- Instructional Material
= Activity
= Interactive Simulation
Intended Users Formats Ratings
- Learners
- Professional/Practitioners
- Educators
- application/java
  • Currently 5.0/5

Rated 5.0 stars by 2 people

Want to rate this material?
Login here!

Access Rights:
Free access
© 2008 Wolfgang Christian
Additional information is available.
Easy Java Simulations, Ejs, OSP, Open Source Physics, classical mechanics, collisions, disk, gas, ideal gas, modeling, two dimensions
Record Creator:
Metadata instance created July 5, 2008 by Mario Belloni
Record Updated:
June 5, 2014 by Andreu Glasmann
Last Update
when Cataloged:
July 1, 2008
Other Collections:

great physics stuff! Ejs Hard Disk Gas Model

Author: lookang
Posted: March 18, 2010 at 5:28AM
Source: The Open Source Physics collection

i love Ejs Hard Disk Gas Model.
i get to learn alot from modifying the codes.

I can't say i know exactly what each line of code is doing but i am presented a way to make sense of the computational physics by changing a bit of the codes and observe what happens.

my remixed work here will run your collision detection codes!

I also notice it is too difficult to run 400 molecules smoothly due to the calculation of the event for 400*400 collisions possible. Will lower it to 50 molecules!

Thanks Prof Wolfgang! going to rate this 5 stars! :)

» reply

Post a new comment on this item
ComPADRE is beta testing Citation Styles!

Record Link
AIP Format
W. Christian, Computer Program EJS HARD DISK GAS MODEL, Version 1.0 (2008), WWW Document, (
W. Christian, Computer Program EJS HARD DISK GAS MODEL, Version 1.0 (2008), <>.
APA Format
Christian, W. (2008). Ejs Hard Disk Gas Model (Version 1.0) [Computer software]. Retrieved August 15, 2022, from
Chicago Format
Christian, Wolfgang. "Ejs Hard Disk Gas Model." Version 1.0. (accessed 15 August 2022).
MLA Format
Christian, Wolfgang. Ejs Hard Disk Gas Model. Vers. 1.0. Computer software. 2008. Java (JRE) 1.5. 15 Aug. 2022 <>.
BibTeX Export Format
@misc{ Author = "Wolfgang Christian", Title = {Ejs Hard Disk Gas Model}, Month = {July}, Year = {2008} }
Refer Export Format

%A Wolfgang Christian %T Ejs Hard Disk Gas Model %D July 1, 2008 %U %O 1.0 %O application/java

EndNote Export Format

%0 Computer Program %A Christian, Wolfgang %D July 1, 2008 %T Ejs Hard Disk Gas Model %7 1.0 %8 July 1, 2008 %U

Disclaimer: ComPADRE offers citation styles as a guide only. We cannot offer interpretations about citations as this is an automated procedure. Please refer to the style manuals in the Citation Source Information area for clarifications.

Citation Source Information

The AIP Style presented is based on information from the AIP Style Manual.

The APA Style presented is based on information from APA Electronic References.

The Chicago Style presented is based on information from Examples of Chicago-Style Documentation.

The MLA Style presented is based on information from the MLA FAQ.

This resource is stored in a shared folder.

You must login to access shared folders.

Ejs Hard Disk Gas Model:

Is Based On Easy Java Simulations Modeling and Authoring Tool

The Ejs tool is needed to explore the computational model.

relation by Anne Cox

Know of another related resource? Login to relate this resource to it.
Save to my folders



Related Materials

Similar Materials