Definitions for "Foucault pendulum"
pendulum with a long wire; can swing in any direction; the change in the swing plane demonstrates the earth's rotation
A pendulum that varies in the direction of its swing as the Earth rotates. Used to demonstrate that it is Earth that rotates and not the sky.
A Foucault pendulum is a simple pendulum (a weight on a long string attached to a support) that tracks the rotation of the Earth. As the pendulum swings, the Earth rotates under the pendulum, so the pendulum seems to rotate. It was first demonstrated by Jean Bernard Léon Foucault, in 1851 at the Paris World's Fair.