The length of a pendulum is the distance from the pivot point to the center of mass of the object that swings back and forth.
Topic 6.1: 6.1 Period of Simple Harmonic Oscillators
Length of Pendulum cheat sheet for homework
The time it takes for one complete swing or oscillation of a pendulum.
The maximum displacement or distance from equilibrium that a pendulum swings.
The number of complete swings or oscillations per unit time for a pendulum.