A centrifuge is the name for any number of devices that spin at a high speed to press objects outward with centrifugal force. They are used to apply specific forces onto a subject in a controlled environment. Centrifuges are used in many different scientific fields, aerospace to chemistry. They are often used to separate items in suspension.

It is easy to see centrifugal force by performing a simple experiment. A person can fill a bucket half way full with water to create a basic centrifuge. In a clear space, the bucket can be quickly spun in a circle, over the head and back down to the ground. The centrifugal force created by spinning the bucket will keep the water inside.

In a real centrifuge, the theory is the same. By spinning a container, whatever is inside is pressed toward the outside of the spin. The centrifuge can contain any number of things, from chemicals to blood to humans. The larger the centrifuge, the more that can be spun with it.

Huge centrifuges are used to expose astronauts to extreme forces. The outward force created by such a large machine can be used to simulate the massive G-forces that an astronaut or fighter pilot is likely to experience. Scientists use the centrifuge to test these forces on people in a controlled environment.

Smaller versions operate in much the same way. Scientists use them to apply specific forces onto a subject in a controlled environment. In medical science, biology, and chemistry, this usually means putting liquids into test tubes, placing them in the centrifuge, and spinning it to apply force to the liquids.

This use of a centrifuge is valuable to scientists because the centrifuge separates liquids into layers based on their mass. More massive components of the liquid are pressed toward the outside of the centrifuge with more force, so they settle to the bottom of the test tube. Less massive components settle in layers higher up, with the least massive at the top. When a doctor or nurse uses a centrifuge on blood, for example, the blood cells collect at the bottom while the blood plasma moves to the top.

By applying controlled forces in a confined space, a centrifuge can be a useful tool not only for scientists, but for other industries as well. Centrifuges are used in wastewater management, in the oil industry, and even in the processing of sugar and milk. They are also used in the nuclear power industry to separate isotopes and enrich uranium.