Energy at High Speed

Kinetic energy, momentum and accelerators

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

• Kinetic energy $K = (\gamma - 1)mc^2$, which reduces to $\frac12 mv^2$ at low speed.
• $E^2 = (pc)^2 + (mc^2)^2$: light has momentum $E/c$.
• Particles in accelerators reach γ in the thousands, within metres per second of c.

Steps

1. Kinetic energy, corrected
2. Newton versus Einstein
3. An old television
4. The Large Hadron Collider
5. Light has momentum
6. Almost light