# Centrifugal Force

by on December 7, 2009

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Have you ever been on one of those park rides where you are spun in a circular room so fast that you are plastered to the wall? You probably felt like a giant hand was pressing down on you. This force that you felt is called a centrifugal force. Another familiar example would be a centrifuge. If you have done some rudimentary studies on biology you would know that is a device used by chemists and biochemist to separate solutions such as blood. It works by spinning a test tube at high rpms and the outward “centrifugal force” does the separation. However there is more to this supposed force than most people realize.

For the most part we try to understand the forces acting on us by our normal senses however in the case of centrifugal forces our senses are wrong. According to physics the centrifugal force as we experience or know it in our daily lives is actually false. Essentially in a stationary frame of reference in classical mechanics it does not exist. What you are actually experiencing is actually the reactive force to a centripetal force. In both the examples the opposite of what you are feeling or you logic leads you to assume is happening. There are actually to forces at different vectors or directions acting on you. One force, the centripetal force is pulling you towards the center of the circular path in this case its the moving wall your are up against. The second force that is acting on is an inertial force. According to physic any object that is motion tends to stay in motion and more importantly tries to move in a straight line. In the case of what you feel as centrifugal force the two different forces exerted on you creates the sensation of a “false” force pressing you against the wall.

What is really happening is that you are wanting fly straight out of the ride but your path is being blocked by the normal or reacting force of the moving wall. However there are situations where the centrifugal force exists. However we simply call it the normal or reacting force. This is the force that sort of cancels out the other forces acting on you. For example the normal or reactive force for gravity is what keeps you from sinking through solid ground. That is because a reactionary force equal to gravity is canceling part of it. This is the only case where a “real” centrifugal force exists.

If you enjoyed this article there are several others that you will enjoy on Universe Today. There is a great article on special relativity. There is also a great article on centripetal acceleration.

There are also some great resources online. There is a Q and A section for students on the Department of Energy website that describes centrifugal force perfectly. The University of Virgina physics website article on it is another good read.

You can also check out Astronomy Cast. Episode 138 Quantum mechanics is a very interesting episode.

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