pendulum
/ˈpɛndjʊləm
/noun
1A weight hung from a fixed point so that it can swing freely, especially a rod with a weight at the end that regulates the mechanism of a clock.If I then release the weight the pendulum begins to swing....
- The early pendulum clocks had short pendulums.
- Until the 1920s, the most accurate timepieces depended on the regular swing of a pendulum.
1.1Used to refer to the tendency of a situation to oscillate between one extreme and another: the pendulum of fashion...
- Sometimes the pendulum is at one extreme or another as the result of the push of forces for change.
- You can see how the pendulum between these two extremes has swung by looking at e-mail.
- Although he wrongly concluded that the periods of oscillation of two pendulums were in the same ratio as their lengths, he later corrected the error.
The use of the pendulum for regulating clocks depends on the principle, discovered by Galileo circa 1602, that for small amplitudes the time of oscillation of a pendulum depends only on its length. A freely suspended pendulum resists changes in its plane of oscillation, a fact employed by Jean Foucault in 1851 to demonstrate the earth’s rotation.
Derivatives
pendular
/ adjective ...- A third pattern of contractions, called pendular movements, manifests itself as swaying motions seen in isolated loops of intestine, probably reflecting rhythmic contractions confined to the longitudinal layer of muscle.
- My feeling is that the moment of inertia and pendular stability is sufficient to retard the pitch change from a single surface deflection.
- Most west European tower bells are chimed at their natural pendular speed; small bells, therefore, sound in faster succession than large bells.
Origin
Mid 17th century: from Latin, neuter (used as a noun) of pendulus 'hanging down'.