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 is observable as directly related to the magnitude of the Coriolis effect. The examples show that the Earth turns underneath the plane of the pendulum swing and how this change in relationship can be interpreted at different latitudes by evaluating the surface velocity components underneath the swing of the pendulum. For a pendulum swing at the North Pole it is shown that the surface velocity vectors of the Earth underneath one side of the pendulum swing are directed in opposition to the velocity vectors underneath the other side of the swing (see Figure 1). The Earth's rotation can then be