NOTE: For better performance, you may download the demonstration by clicking here. If you have not already downloaded and installed the free CDF player, it is available here.

In this demonstration, you can observe the relationship $v\propto\frac{1}{\sqrt{r}}$ for planets with circular orbits. The graph on the right shows the speeds and radii of all five planets. Use the slider to set the radius of the red planet and observe how its speed changes.