The Ejs Two Orbiting Masses with Relative Motion model displays the dynamics of two masses orbiting each other subject to Newtonian gravity.  The simulation displays the motion of the masses in the inertial reference frame and the relative motion as seen from one of the masses.  The initial energy of the system can be changed via textbox and the ratio of masses can be changed via a slider.  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 Two Orbiting Masses with Relative Motion 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_ehu_central_forces_relative.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.

Please note that this resource requires at least version 1.5 of Java (JRE).