The Ejs Spring Pendulum model displays the model of a hollow mass that moves along a rigid rod that is also connected to a spring.  The mass, therefore, undergoes a combination of spring and pendulum oscillations.  The initial position and velocities, as well as the spring constant can be changed via textboxes.  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 Spring Pendulum 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_oscillations_elastic.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 (JRE).