Description

This applet is a simulation of a body in motion in a gravitational field.

Purpose

This applet illustrates a number of properties of gravity. The first property that it shows is how changing the initial velocity of the body will affect the eccentricity of its orbit. If the body has just the right velocity perpendicular to the direction from its center to the center of the body of attraction, then it will orbit in a circle. Any faster or slower will result in ellipses of varying degrees of eccentricity. By varying the velocity, the user can set a body in a round orbit (like a planet) or in a highly eccentric orbit (like a comet). The second property that this simulation shows is how the axis of the orbit will rotate or "process" over time. This is a phenomenon that was predicted by Einstein's General Theory of Relativity.

Features

• Direct Manipulation
  This simulation uses intuitive direct manipulation to place the object and to drag out its velocity vector. This direct manipulation makes it feel like you are actually interacting with the gravity well object.
  
  
• Motion Paths
  The moving object leaves behind a path which shows the motion of the object over time. This is an example of where the simulated experiment can show things that a real, physical experiment often can't.