Pendulums

Nature’s clock

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

• For small swings, $T = 2\pi\sqrt{L/g}$: it depends only on the length and on gravity.
• $T \propto \sqrt{L}$: four times the length gives twice the period.
• Mass and (small) amplitude don’t matter, which is why pendulums make good clocks.

Steps

1. Heavier bob
2. Swing
3. The pendulum formula
4. One metre
5. Twice as slow
6. Grandfather clock
7. On the Moon