To begin, consider a Foucault pendulum1–3 from a nonrotating-frame perspective. As it swings back and forth in a fixed vertical plane, Earth is slowly rotating beneath it about a line through the pendulum’s point of suspension and its equilibrium position. In the northern hemisphere, the rotation is counterclockwise and given by where ωE is Earth’s angular velocity [2π/(24 h)],4 λ is the latitude of the pendulum’s location, and ωλ is the rate of rotation beneath the pendulum. By contrast, when viewed from a rotating-frame perspective (Earth), the pendulum appears to be precessing clockwise. The cause5 of this precession is understood to be the Coriolis effect. In this paper, it will be shown how the Coriolis effect causes the Foucault pendulum to precess.
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The pendulum’s back-and-forth cycle consists of four distinct motions,6 two in...
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