The EJS Lennard-Jones Potential model shows the dynamics of a particle of mass m within this potential.  You can drag particle to change its position and you can drag the energy-line to change its total energy.

The Lennard-Jones potential function is a reasonably accurate model of interactions between noble gas atoms.  The binding energy epsilon is the depth of the potential well and minimum molecular separation are set equal to unity.  This simulation uses uses a natural system of units the mass and the depth of the Lennard-Jones potential set equal to 1. For argon (for example), the unit of distance is 3.4 angstroms, the unit of mass is 40 atomic mass units, and the unit of energy is 0.01 electron-volts; the corresponding unit of time is then 2.2 picoseconds, the unit of velocity is 160 meters per second.

The Lennard-Jones Potential 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_stp_md_LennardJonesPotential.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 classical 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.