Coupled Pendula

DCS Code: 3A70.27 Last Updated: March 27, 2026
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Purpose

Two pendula coupled by a spring demonstrate periodic energy transfer between oscillators. Students observe beat patterns, normal modes (symmetric and antisymmetric), and complete energy exchange through weak coupling.

Two cylindrical pendulum masses (one with red tape, one with blue tape) hanging from metal rods on a horizontal bar, connected by a coiled spring near the bottom, mounted on a frame with two vertical posts and a white base
Figure 1: Coupled pendula apparatus: two masses connected by a spring, suspended from pivoting rods on a horizontal bar. Displacing one pendulum causes oscillation energy to transfer completely to the other and back.
Demo Apparatus