How the scientist measures the rotation of earth, means RPM of earth, Which instruments use, and how it Works?

How the scientist measures the rotation of earth, means RPM of earth, Which instruments use, and how it Works?

A Foucault pendulum is the device that is used to demonstrate that the earth rotates about it axis [1]. It works in accordance to Newton’s laws of motion.

Since the Earth rotates once every 24 hours, it rotates at .000694 RPM.

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