Foucault Pendulum
The Foucault Pendulum is a demonstration of a fact that we take for granted: the Earth rotates! Every day, Columbus, Ohio revolves around the Earth at 790 mph. As the Earth moves, it carries COSI with it, and COSI carries the pendulum. When you watch the swinging pendulum over time, it will appear to travel around the base. In reality, the pendulum is always swinging in the same plane. It is the Earth’s rotation under the pendulum that causes this illusion.COSI's Foucault Pendulum shows visitors our recreation of French physicist Jean Foucault's experiment to prove the Earth's rotation on its axis. Knowing Newton's first law of motion that an object that is free from all outside forces travels at a constant velocity along a straight line path, the only way for the pendulum to trace out the path along the circle is for the Earth to rotate under the pendulum.
This pendulum knocks steel balls from their resting place as the pendulum sweeps out the circular path. The balls are set so two will be struck about every fifteen minutes.
Do At Home Activity
Take a piece of string about two feet long and tie something small and heavy onto it. A set of keys, a heavy washer, or a small amount of clay works nicely. You can also use a yo-yo.This becomes the bob of the pendulum. Hold onto the other end of the string and extend your arm. Start the bob swinging.
As the string and bob swing back and forth, hold your hands steady and walk around the swinging bob in a circle. The plane of the bob apperas to change as you move, but it is really still swinging in the same plane as when it started.
That is also what happens to the Foucault Pendulum as the earth rotates on its axis!