Dimensional Analysis

Checking physics with units alone

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Both sides of an equation must have the same dimensions.
• Units can expose wrong formulas, but not wrong numerical factors.
• Matching dimensions can predict how a quantity depends on others.

Steps

1. Dimensions
2. Spot the impossible formula
3. Deriving a formula
4. Dimensions of energy
5. What units can’t tell you
6. Find the pendulum formula
7. Waves on a string