EVERYBODY KNOWS that the period of a pendulum is proportional to the (square root of the) length of the line suspending the weight. The longer the pendulum, the slower it swings (i.e. the longer the period).
So . . . some kid at Harvard built a device with a series of 15 pendulums in a row, each one slightly longer than its neighbor, set them in motion, and filmed the result . . . fascinating to watch, think about, and try to explain:
"Pendulum" is derived from the Latin "pendulus", of course, meaning "hanging". Pendulums were used as the most accurate form of time-keeping from the time of Galileo, who discovered their basic properties, until the 1930s.
Today's Bird HERE