The precession of a Foucault pendulum viewed as a beat phenomenon of a conical pendulum subject to a Coriolis force

Abstract

A conical pendulum has slightly different frequencies of vibration when it rotates clockwise or anticlockwise in a laboratory on a rotating Earth. This splitting of the frequency is due to the presence of the Lorentzlike Coriolis force which presses either radially inward or outward on the pendulum bob depending on the sense with which it traverses its circular orbit. The precession of the plane of a Foucault pendulum may be viewed as a beat phenomenon in the planar superposition of the clockwise and anticlockwise circular motions of the conical pendulum.