Every object in the universe has an escape velocity. Launch a projectile faster than this velocity and it will never return to the surface. Any slower, and eventually it will fall back to where it came from. In the next few demonstrations, you can experiment with projectiles of different speeds, and planets of different masses and radii.

In this demonstration, the planet has a fixed mass and radius, and you can control the launch velocity of the projectile using the slider. Set the projectile’s launch velocity and click the Launch button to launch the projectile. Depending on the launch velocity, the object either falls back down to the planet or escapes from the planet.