A centrifuge is a spinning device used to separate materials of different densities. Centrifuges are used industrially to separate impurities from products such as milk, lubricating oils, beer, and wine. They are also used in scientific research as a separation tool. In genetic research, for example, high-speed centrifuges are used to separate viruses, small cell components, and even individual protein and nucleic acid molecules.

Centrifuges work on the principle of centrifugal force and its counterpart, centripetal force. The relationship between these two forces can be demonstrated by considering the analogy of a person swinging a liquid-filled bucket on a rope. As the bucket is swung in a circle, it tends to pull outward, but the rope keeps it from flying away. The pull on the rope away from that person is called centrifugal force, and the tension of the rope that keeps the bucket from flying away is...