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 observed in relation to the pendulum swing. At the North Pole the support-point of the pendulum swing is located on the axis of rotation of the Earth. No matter what vertical orientation is established by the plane of the swing, the relative velocity vectors of the Earth's surface on opposite sides and equidistant from the center point of the swing will be in opposition. The Earth turns underneath the plane of the pendulum swing that is established. The support-point of the connection turns with the Earth and is depicted as freely suspended above the Earth. The plane of the pendulum