The period of a pendulum is the time it takes to complete one complete oscillation (e.g. from one side to the other and back again). In the absence of air resistance, the period (T) depends only on the length of the pendulum (l) and the gravitational field strength (g).
The formula for the period is:

where:
T is the period
L is the length of the pendulum
g is the gravitational field strength
The Swinging Pendulum Simulation
This simulation visually demonstrates the motion of a simple pendulum. Users can input the length of the pendulum (in meters) and the gravitational field strength (in N/kg). Once started, the pendulum begins to swing back and forth in smooth harmonic motion, and the simulation calculates and displays the pendulum’s period based on the given inputs.