Pendulum 2.5 m long: find its period

A simple pendulum 2.5 m long swings through a small angle (g = 10 m/s²). Find its period.

Step-by-step

1. T = 2π√(L/g) = 2π√(2.5/10) ≈ 3.1416
   For small swings a pendulum's period depends only on its length and gravity

Why it works

For small swings a simple pendulum is simple harmonic: T = 2π√(L/g), so only the length and g matter, not the mass of the bob or how wide it swings.

Common mistakes

• Thinking a heavier bob swings more slowly.
• Measuring the length down to the floor instead of from the pivot to the bob.

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