Escape Velocity

Leaving for good

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Escape speed $v_\text{esc} = \sqrt{2GM/R} = \sqrt2 \times$ the circular orbit speed.
• About 11.2 km/s from Earth and 2.4 km/s from the Moon.
• When the escape speed exceeds the speed of light, you have a black hole.

Steps

1. Throw it hard enough
2. Break free
3. The escape speed formula
4. Compare
5. The Moon’s missing air
6. Black holes