Foucault pendulum sharing the rotation of the earth about its own axis, the suspension point of the pendulum traces out a circular path during one sidereal day. At the latitude of Paris, 48 degrees 51 minutes north, a full precession cycle takes just under 32 hours, so after one sidereal day, when the Earth is back in the same orientation as one sidereal day before, the oscillation plane has turned by just over 270 degrees. If the plane of swing was north-south at the outset, it is east-west one sidereal day later. This also implies that there has been exchange of momentum;
Foucault pendulum vector diagrams at the equator to zero at the pole even though the angular velocities are all the same. formula_1 = formula_2 = formula_3 The ratio of the surface velocity at two given latitudes is equal to the ratio of the cosine for the two given latitudes. formula_4 = formula_5 = formula_6 The time to observe one full rotation of the Earth in relation to the plane of a swinging pendulum is one day at the poles (the minimum time) and cannot be observed (infinitely long, the maximum time) at the equator. One of the great insights by Léon Foucault is to