Pendulum Simulator
Swing several pendulums at once and discover what really sets their rhythm: length, gravity and how far you pull them back.
This is a real nonlinear pendulum, integrated with RK4 — not the small-angle shortcut. Pick a preset or tap a bob to read its length, gravity, period and frequency in real units, and see how the true period grows for big swings.
Presets
Selected pendulum
Tap a bob to inspect its length, gravity, period and frequency.
Formulas & sources
T = 2π√(L/g)
θ″ = −(g/L)·sin θ
T = 4√(L/g)·K(sin(θ₀/2))
g₀ = 9.80665 m/s²
The units and constants behind this swing
A pendulum is a machine made of three quantities. Follow any of them into the converter, or into the constant that defines it — something a physics simulation alone cannot show you.
What you are changing
The constant in the formula
- g₀ = 9.80665 m/s² Standard gravity · a defined value, exact — not a measurement
The same 1-metre pendulum, moved around the Solar System
| Body | g (m/s²) | Period of a 1 m pendulum | vs Earth |
|---|---|---|---|
| Earth | 9.80665 * | 2.01 s | 1.00× |
| Moon | 1.62 | 4.94 s | 0.17× |
| Mars | 3.721 | 3.26 s | 0.38× |
| Venus | 8.87 | 2.11 s | 0.90× |
| Mercury | 3.7 | 3.27 s | 0.38× |
| Jupiter | 24.79 | 1.26 s | 2.53× |
| Saturn | 10.44 | 1.94 s | 1.06× |
| Sun | 274 | 0.38 s | 27.94× |
Periods are calculated live from T = 2π√(L/g) with L = 1 m. * Earth's value is the defined standard gravity g₀; the others are NASA surface-gravity figures (NIST, NASA Planetary Fact Sheet).
The pendulum that almost became the metre
A pendulum whose full swing takes exactly 2 seconds needs a length of 0.9936 m on Earth — so close to one metre that in the 17th century it was proposed as the definition of the metre itself. The definition went to the speed of light instead, but the coincidence is still there in the numbers above.
How the units are actually defined →