What is Simple Harmonic Motion (SHM)?
Simple harmonic motion (SHM) is a type of periodic motion characterized by a restorative force equal and opposite the source of displacement...fortunately for us, our surrounding atmosphere provides that force for sound waves, returning it to the ambient pressure when the source of displacement is at rest. Demonstrations of simple harmonic motion are approximated by the movement of a small-angle pendulum and/or a mass/spring example, both of which are shown on the videos below. The periodic movements of both are represented as tracing a sine wave in the time domain, which takes the shape of its mathematical namesake, the sine function. A sinusoidal wave (which also includes a cosine wave) is the only waveform that produces a single frequency, as can be seen in the waveform chapter. With any minute deviations in the sine shape, additional frequencies will be generated.