Harmonograph (Lissajous figures)
This activity belongs to the GeoGebra book The Domain of the Time.
By combining two SHM with perpendicular directions, having the same period and in the same phase, we get a straight line. If we shift their phases, we get ellipses. If they also have different periods, we obtain Lissajous curves.
As we will see later, the motion of a pendulum with a sufficiently small amplitude is almost identical to SHM. Therefore, the combined action of two perpendicular pendulums also produces Lissajous figures. These devices are called harmonographs.
Author of the activity and GeoGebra construction: Rafael Losada.