Simple pendulum

Theory

A small bob on a light string can help us measure gravity. For a small swing angle, the simple-pendulum model links the period to length and gravitational acceleration. It treats friction as negligible and assumes the string does not stretch.

Measure the time for several full oscillations, then divide by their number to find T. Plot T² vertically against L in metres horizontally. The best-fit line has slope 4π²/g, giving a way to estimate g. Here, L runs from the pivot to the centre of the bob.

T = 2π√(L/g)

T is one oscillation’s period in s; L is pivot-to-bob-centre length in m; g is gravitational acceleration in m/s².