Why would someone using a Foucault Pendulum at the equator say that Earth does not rotate?
A person using a Foucault Pendulum at the equator might say that the Earth does not rotate because the pendulum's motion appears to be in a straight line rather than rotating like it does at other latitudes.
To understand why this happens, we need to first understand what a Foucault Pendulum is. It is a simple pendulum with a long wire or chain attached to a weight or bob at its lower end. When set in motion, the pendulum swings back and forth in a steady plane due to the force of gravity. However, due to the rotation of the Earth, the plane of swing appears to rotate over time.
At the poles, where the rotation is most noticeable, the pendulum will complete a full rotation in about 24 hours. As we move away from the poles towards the equator, the rotation speed decreases. At the equator, the pendulum's motion appears to be in a straight line, from side to side, without any rotation.
The reason for this is related to the Earth's rotation axis. The rotation axis passes through the poles, so at the equator, the pendulum's plane of swing aligns with the Earth's axis and therefore appears to show motion only in a straight line. If the Earth didn't rotate, the pendulum would have a fixed plane of swing.
So, when someone using a Foucault Pendulum at the equator observes its motion in a straight line, they might conclude that the Earth does not rotate, when in fact it does. This misconception arises because they are not able to observe the apparent rotation due to the alignment of the pendulum's plane of swing with the Earth's axis at that particular location.