Pendulum

The pendulum may be defined as a mass of weight suspended from a pivot or hinge from which it can swing freely. The force of gravity, one that ensures that all objects that go up eventually come down, ensures that after the object swings for a while, it reaches a state of rest or equilibrium after revolving round the equilibrium position. The Illustration of a pendulum is one of the most central concepts in physics today, and involves suspending a bob from a massless string. When the bob is displaced, it swings about a central point under the influence of gravity.

[edit] Uses

Pendulums have major uses in everyday living like timekeeping; some clocks are made of them. This is largely made possible by the principle of inertia which states that a body will continue in its state of rest, or uniform motion along a straight line unless acted upon by an external force to do otherwise. The pendulum can also be used to measure acceleration due to gravity, symbolized by g, which is a very important concept in proving that the shape of the earth is spherical and that the earth spins.

In divination, a pendulum can be used be a psychic to find the answer to questions, in a similar method to the planchette or Ouija board.

[edit] Foucault’s pendulum

A long time ago, almost everyone thought that the earth was a flat static object. The Foucault’s pendulum originated in a bid to prove that the earth rotates. It was invented by French physicist named Bernard Leon Foucault in 1819. Foucault’s viewpoint was that if he displaced a pendulum from a static point, and the direction of its swing kept changing, the only possible reason could be that the earth was moving. He was able to prove that the pendulum could trace a complete 360 degrees if left for a period of time, say 32 hours. During the course of this experiment, he was able to deduce that effects such as gravity, friction and air resistance could cause a swinging pendulum to come to a final stop. In order to be able to demonstrate this experiment to people, he had to make it swing for a while. To achieve this, he had the option of increasing the weight of the pendulum, the length of the wire or both.

The Foucault’s pendulum can be illustrated through the use of it revolving around any vertical plane. The direction in which a pendulum swings, changes with time as a result of the earth’s rotation. The first public illustration of this experiment took place in the Meridian Room of Paris Observatory. This illustration caused a lot of sensations because the earth had been believed to be static at that period. The plane of oscillation of a pendulum always remains fixed and is relative to the earth’s position. This is in accordance with what Foucault noticed in the seventeenth century, that even if you vary the point from which a pendulum swings, it still continues to swing in the same direction.

The pendulum Foucault used in 1851 at the Pantheon was relocated to the Conservatoire des Arts ET Métiers in Paris, a public museum and was a star attraction for several decades to come. Today, there are lots of pendula around the world and most of them are seen in museums and schools.