19-05-2017, 10:40 AM
A pendulum is a weight suspended from a pivot so it can move freely. When a pendulum moves laterally from its equilibrium rest position, it is subjected to a restoring force due to gravity which will accelerate it back towards the equilibrium position. When released, the recoil force combined with the mass of the pendulum causes it to oscillate around the equilibrium position, swinging back and forth. The time for a complete cycle, a left turn and a right turn, is called the period. The period depends on the length of the pendulum and also a slight degree on the amplitude, the width of the pendulum oscillation.
From the earliest scientific investigations of the pendulum around 1602 by Galileo Galilei, the regular movement of the pendulums was used for timing, and was the most accurate watch technology in the world until the 1930s. The pendulum clock invented by Christian Huygens in 1658 became the world's standard chronometer, used in homes and offices for 270 years, and reached the accuracy of approximately one second per year before being replaced by the years quartz watch thirty. Pendulums are also used in scientific instruments such as accelerometers and seismometers. Historically they were used as gravimetros to measure the acceleration of the gravity in the geophysical surveys, and even as a standard of length. The word "pendulum" is a new Latin, from the Latin pendulus, which means "to hang".
It can be understood in the following video: