What is a Centrifuge?

science engineering

A centrifuge is any number of devices that spin at a high speed to press objects outward with centrifugal force. It is easy to see centrifugal force by performing a simple experiment. Fill a bucket half way full with water. A large tumbler will work as well, but it isn't as easy to use. Now you have a basic centrifuge.

Find a clear space where you won't hit anything or anyone with your centrifuge. With your arm at your side, quickly spin it in a circle, up over your head and back down to the ground. The centrifugal force created by spinning the bucket or tumbler will keep the water inside. This is a simple example of a centrifuge.

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 you can spin with it.

NASA has a huge centrifuge, which it uses to expose astronauts to extreme forces. The outward force created by the monstrous centrifuge can be used to simulate the massive G-forces that an astronaut will experience during the take off of a space shuttle. NASA scientists use the centrifuge to test these forces on people in a controlled environment.

Smaller versions of this centrifuge 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 to many branches of science. From aerospace to chemistry to medicine, many scientists would find themselves unable to perform many important tasks without the use of a centrifuge.

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Posted by: nathan
There is no such thing as "centrifugal" force. It is a made-up force that is named after the centrifuge. The concept of a "centrifugal" force is a result of poor physical analysis of certain situations. Suppose you have books on your seat next to you in your car. You turn a corner sharply and the books go flying and hit the opposite side of the car. You might say that this is an example of "centrifugal" force, but what really happened was a result of Newton's First Law. When the car makes a quick turn, the books will continue to travel with their previous velocity until acted on by "an outside force." The friction between the books and the seat is the force that acts. Friction, however, was not able to stop the books from continuing on their previous path. Thus the books went flying against the car. I hope this post is helpful. Keep up the good work.
Posted by: pearlsawme
If friction was able to stop the books from continuing on their previous path, then the frictional force is the necessary centripetal force to keep the book going in a circular motion. Both the car and book move along a circle. By Newton's third law, friction was a reaction force to some other action force. Without going into detail about the action force, action force (centrifugal) is opposite to the direction of the reaction force (centripetal force). The action force is the centrifugal force and it does not act on the book and however it acts on the agent which produced the frictional force. Hence it is not correct to say that there is no such thing as "centrifugal" force. However, a book that goes flying off is not due to centrifugal force, rather it is due to inertia in the absence of frictional force. In that case, there is no centripetal force on the book and hence no centrifugal force which are action reaction pair.
Posted by: anon8427
Washing machine also use centripetal force to squeeze water from the clothes being washed.

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