Gravitational model

The first model is a simple gravitational model, which calculates the net gravitational force on each body from all other bodies, and hence the acceleration and velocity of each body, and the distance travelled after an interval of time. Given a set of bodies, each with initial {X,Y) locations and X,Y velocities, new locations are found for each body after a short interval of time. This process is repeated indefinitely.

In this applet, a planet and a string of satellites radiating from it are given an initial set of (slightly randomized) velocities. Those which have too high velocities escape from the planet. Those which move too slowly fall onto the planet (the impacts marked by flashes). The remainder orbit the planet in elliptical orbits.

Each simulation is started/stopped by clicking on the Start/Stop button. With Motion trails unticked, bodies and cables are shown at their present location. In Show trails ticked, bodies and cable motion leaves a trail. The Hold option fixes the radial distance of the lowest body in the tower. The Feed option allows bodies to be fed into the base of a rising tower. The Release option breaks the cable connecting the lowest tower body to the planet. The Shatter option breaks all cables in a tower.

Applets can be restarted by returning to this page, and then reselecting them. Where the models have randomized initialization (as in the Gravitational model and the Elastic model), a new simulation starts each time the applet begins.