Simple Pendulum Period
A pendulum’s period depends only on its length and gravity, not its mass or (for small swings) its amplitude — which is why it keeps time.
The period is T = 2π·√(L/g). where L is the pendulum length and g gravity.
Apply the simple-pendulum period formula.
Results
A one-metre pendulum swings in about two seconds. Lengthening it slows the swing; the independence from mass is what makes it a reliable clock element.