Real pendulums are subject to friction and air drag, so the amplitude of their swings declines. When given an initial push, it will swing back and forth at a constant amplitude. This is a weight (or bob) on the end of a massless cord suspended from a pivot, without friction. The simple gravity pendulum is an idealized mathematical model of a pendulum. The word pendulum is new Latin, from the Latin pendulus, meaning hanging. Historically they were used as gravimeters to measure the acceleration of gravity in geo-physical surveys, and even as a standard of length. Pendulums are also used in scientific instruments such as accelerometers and seismometers. The pendulum clock invented by Christiaan Huygens in 1656 became the world's standard timekeeper, used in homes and offices for 270 years, and achieved accuracy of about one second per year before it was superseded as a time standard by the quartz clock in the 1930s. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing.įrom the first scientific investigations of the pendulum 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.

The time for one complete cycle, a left swing and a right swing, is called the period. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. 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. 'Simple gravity pendulum' model assumes no friction or air resistance.Ī pendulum is a weight suspended from a pivot so that it can swing freely.

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