# Pendulum

A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force combined with the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. A pendulum swings with a specific period which depends (mainly) on its length.

From its discovery around 1602 by Galileo Galilei the regular motion of pendulums was used for timekeeping, and was the world's most accurate timekeeping technology until the 1930s. Pendulums are used to regulate pendulum clocks, and are used in scientific instruments such as accelerometers and seismometers. Historically they were used as gravimeters to measure the acceleration of gravity in geophysical surveys, and even as a standard of length. The word 'pendulum' is new Latin, from the Latin pendulus, meaning 'hanging'.

The simple gravity pendulum is an idealized mathematical model of a pendulum. This is a weight (or bob) on the end of a massless cord suspended from a pivot, without friction. When given an initial push, it will swing back and forth at a constant amplitude. Real pendulums are subject to friction and air drag, so the amplitude of their swings declines.

### Other articles related to "pendulum, pendulums":

Shortt-Synchronome Clock
... The Shortt-Synchronome free pendulum clock was a complex precision electromechanical pendulum clock invented in 1921 by British railway engineer William Hamilton Shortt in collaboration with horologist Frank Hope-Jones ... They were the most accurate pendulum clocks ever commercially produced, and became the highest standard for timekeeping between the 1920s and the 1940s, after which mechanical clocks ... Shortt clocks kept time with two pendulums, a master pendulum swinging in a vacuum tank and a slave pendulum in a separate clock, which was synchronized to the ...
Pendulum - Other Uses - Execution
... During the Middle Ages, pendulums were used as a method of torture by the Spanish Inquisition ... Using the basic principle of the pendulum, the weight (bob) is replaced by an axe head ... With each pass, or return, the pendulum is lowered, gradually coming closer to the victim's torso, until finally cleaved ...
Shortt-Synchronome Clock - How It Works
... The master and slave pendulums were linked together in a feedback loop which kept the slave synchronized with the master ... using a 15-tooth count wheel which was moved forward each pendulum swing by a pawl attached to the pendulum ... a gravity lever which gave the slave pendulum a push ...
List Of Pokémon (52–101) - Hypno
... It always carries its favorite pendulum in its hand, which it uses to put others to sleep ... It does so by swinging the pendulum, which it carries in its hand all the time ... When hunting for prey, it will polish the mysterious pendulum ...
Spring Pendulum
... A spring pendulum is a physical system where a piece of mass is connected to a spring so that the resulting motion contains elements of a simple pendulum as well as a spring ... The system is much more complex than a simple pendulum because the properties of the spring adds an extra dimension of freedom to the system ... is the possibility that the spring has a range that is overtaken by the motion of the pendulum, making it practically neutral to the motion of the ...

### Famous quotes containing the word pendulum:

The pendulum oscillates between these two terms: Suffering—that opens a window on the real and is the main condition of the artistic experience, and Boredom ... that must be considered as the most tolerable because the most durable of human evils.
Samuel Beckett (1906–1989)

During the first World War women in the United States had a chance to try their capacities in wider fields of executive leadership in industry. Must we always wait for war to give us opportunity? And must the pendulum always swing back in the busy world of work and workers during times of peace?
Mary Barnett Gilson (1877–?)