This WebApp is a virtual system simulator. This is its main menu. You can drag the mouse to bring each "folder" forward or backward to select a system. Each folder leads to its corresponding simulation.
For each system there is a standard interface where you can interact with. On each one there is a help link on the top right part of the screen. Also, each system can be accessed remotely via a simple web-socket text protocol (see this blogpost for details).
The systems are simulated using Runge-Kutta or Euler methods with a integration step small enough for them to rum relatively fast and smooth on most of the browsers. Several technical aspects are abstracted away by the app, like the springs deforming, wheels spinning, etc. The goal is to provide a visually realistic and aesthetic feedback to the user. It is important to notice that the goal is to simulate the traditional dynamic for each system, hence, some discontinuities and non-linearities that are not part fo the model are not simulated. For example, the springs can stretch indefinitely, pass through the blocs, etc.
Finally, as a cool reference to the app, notice that this menu itself moves and behaves dynamically. Can you figure out what kind of model is behind the movement of the items on this menu?

Press OK to details of the items in this menu.