The EJS Newton's Mountain model illustrates the motion of a projectile launched from the top of a VERY tall mountain on Earth. The diagram shown in the simulation is taken from Newton's A Treatise on the System of the World, which he wrote after the Principia, but the basic idea is found in the Principia itself. Newton concluded that a projectile launched horizontally with sufficient speed would orbit Earth rather than crashing to Earth's surface. Thus the motion of a projectile fired on Earth was not qualitatively different from that of the moon orbiting Earth.  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 Newton's Mountain 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_astronomy_NewtonsMountain.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 astronomy 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).