Foucault’s pendulum proves Earth’s rotation. In the Northern Hemisphere, the pendulum rotates clockwise. In the Southern Hemisphere, it rotates counterclockwise. The pendulum turns faster if it is closer to the pole. On the Equator, the pendulum does not rotate.
Flat-Earthers invented various excuses to discredit Foucault’s pendulum. In reality, anyone not near the Equator can easily repeat the experiment, and it will give the expected result.
The Foucault pendulum will rotate with an angular velocity of 360° × sin φ per day, where φ is the latitude of the pendulum’s location. It rotates clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. There is only one explanation for why Foucault’s pendulum behaves like that: the Earth is a rotating sphere.
References
- Foucault pendulum – Wikipedia
- How do flat Earthers explain the Foucault pendulum? – Quora