Two-bodies with different masses orbit about their common center of mass.
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.
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.
Instructions: To customize the simulation do the following:
Run the Two Body Orbits jar and set options to create a custom configuration.
Create html, pdf or text documents and place them into the same directory as the jar file.
Enter the document filename(s) into the doc user interface field or clear that field to disable documentation. You may enter multiple filenames if they are separated by a semicolon and you may enter a URL beginning with the characters http:.
Select the “student” checkbox to create a custom jar file.
Enter a jar file name, such as exercise5.jar, in the Save dialog. Note the check-box in the dialog allows you to generate a HTML page that runs the newly created jar file as an applet.
The customized jar file contains the customized initial conditions and the documents that were entered in step 3 and can now be distributed.
Users (students) run the jar file and access the packaged documentation using Documentation button
in the main window.
Note: Teachers can save their preliminary work by clicking the "teacher" box. The repacked jar file can later be opened to continue the customization.
EJS programmers can further customize this model but we ask that they give attribution to this original model and use a new and unique jar name for their modified model to avoid confusion with the original jar.
The Two Body Orbits model for teachers was developed by Wolfgang Christian using the Easy Java Simulations (EJS) modeling tool. You can examine and modify the model for this simulation if you have EJS version 4.3 installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu.
Information about Ejs is available at: <http://www.um.es/fem/Ejs/> and in the OSP ComPADRE collection <http://www.compadre.org/OSP/>.