The approximate period is T = 2π√(L/g), where L is the pivot-to-bob length. At the same gravity, making the length four times as large makes the period twice as large. Changing mass alone leaves this ideal period unchanged. The model limits starting angles to keep the approximation appropriate.
Forces, motion and energy · Discover & try
What changes a pendulum’s swing time?
Reading level 3 of 5 · IndependentChange
Word help
Period
The time for one complete repeating cycle.
Amplitude
The largest displacement from equilibrium in an oscillation.
Pivot
The fixed support about which the pendulum swings.
Watch · Try · Explain
See how it works
The interactive activity is loading.
Ideal small-angle pendulum with a massless fixed-length string; no damping or large-angle correction.
What to look for
- Count a complete cycle, not one crossing.
- Change mass while keeping length fixed.
- Compare period with the square root of length.
Explain what you noticed
A separate ideal small-angle pendulum has its length increased from 0.5 m to 2 m at the same gravity. How does its period change?
Keep this idea: For small swings in the ideal model, length and gravity set period; bob mass does not.
Follow the sources
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
You’ve reached the end of this journey
Choose another journey →