You are piloting the space shuttle, trying to catch up with the space station, which is in the same orbit as you, but 15 degrees ahead. What should you do to catch up after exactly one orbit (about 90 minutes)? Fire the engines to increase your speed, or fire the engines to decrease your speed? Enter the factor by which you want to change your speed in order to catch up.
The units in the animation are Mega-meters, kg, and hours. Each grid is 0.5 Mega-meters, and each time step is 15 seconds. The default radius corresponds to a low-earth orbit of 700 km above the Earth's surface (twice the actual ISS altitude). The initial angle can be positive or negative. Click on a point in the animation to display the x and y coordinates. In the vector displays, the vector components are blue arrows, while the resultant vector is displayed in red.
The central mass is that of the Earth. Newton's law is integrated numerically by a Runge-Kutta algorithm for each of the two objects (which interact only with the Earth, not with each other).
By Robert Johnson, using the Physlet Animator and dataGraph classes from Wolfgang Christian and Mario Belloni.