Introduction to Foucault's Pendulum:Foucault's Pendulum is a gold-plated sphere containing some copper that is suspended from a 75-foot ceiling by a stainless steel wire. The universal joint allows it to swing freely in any direction. An electromagnet underneath Foucault's pendulum counteracts air friction, allowing the pendulum to continue to swing evenly. Due to the Earth's rotation, the direction of the pendulum's swing appears to change throughout the day, taking 36 hours and 45 minutes to complete one cycle.