Pendulum

A gravity pendulum (plural pendula) is a weight on the end of a rigid rod (or a string/rope), which, when given an initial push, will swing back and forth under the influence of gravity over its central (lowest) point. A torsion pendulum consists of a body suspended by a fine wire or elastic fiber in such a way that it executes rotational oscillations as the suspending wire or fiber twists and untwists. Another variety of a torsion pendulum is a fixed elastic coil connected to a rod-like object; once moved off its resting position, the coil will set the rod into an oscillatory motion.

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Galileo Galilei discovered that pendula exhibit regular periodic motion, a feature which he correctly speculated would make them useful for timekeeping devices such as clocks. This has led to their frequent metaphorical use as a way of describing the passage of time, or the experience of it. The mass of the weight on the pendulum does not affect the outcome, just as it does not affect the outcome of dropped objects. (It is said that Galileo made this discovery while, as a seventeen-year-old, watching the swinging chandeliers in the cathedral of Pisa.)

Related Topics:
Galileo Galilei - Periodic motion - Time

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