written by Wolfgang Christian

The Two Body Orbits model for teachers shows the motion of two objects (binary star or moon-planet system) interacting via Newton's law of universal gravitation.  It is designed to teach physics, Earth science, and environmental science topics by showing the spatial path of objects around their common center of mass (barycenter).  An optional 3D view shows the celestial sphere and and the orbital plane (ecliptic).  Default units are chosen for Earth obit about our Sun so that the distance unit is one astronomical unit and the time unit is one year. The size (radius) of the spherical objects is not to scale.
 
An important feature of the ready-to-run Two Body Orbits simulation is that it can be customized by teachers to meet various learning objectives. The teacher sets the ratio of the two masses, their initial positions and velocities, and various visualization and scale parameters.  Documentation, such as an exercise or lesson, can be added to the simulation by entering a filename into the Customization dialog.  Selecting the "student" checkbox creates a ready-to-run package with the new configuration without the Customization dialog.

The Two Body Orbits model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run Java archive.  Double clicking the ejs_mech_orbits_TwoBodyOrbits.jar file will run the program if Java is installed.  EJS is a part of the Open Source Physics Project and is available in the OSP Collection.

• Download ejs_TwoBodyOrbits.jar - 1830kb Java Archive File

Published July 13, 2012
Last Modified June 24, 2015

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A pdf file that provides additional documentation regarding customization of this (these) simulations.

• Download 2body_documentation.pdf - 188kb Adobe PDF Document

Published August 17, 2012
Last Modified August 17, 2012

This file is included in the full-text index.

The source code zip archive contains an XML representation of the Two Body Orbits model.   Unzip this archive in your EJS workspace to compile and run this model using EJS.

• Download ejs_mech_orbits_TwoBodyOrbits.zip - 59kb Compressed File

Last Modified June 13, 2014

This file has previous versions.