Centrifugal force

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Centrifugal force is actually not a force but the experience of an inertial force experienced in a rotating reference frame acting away from the center of the rotation. It is equal in magnitude but opposite to the centripetal force required to constrain the body to move in a circular motion.

Velocity is a vector quantity; that is, it has magnitude (speed) and direction. If a body is travelling at a certain speed and in a certain direction undisturbed it has constant velocity. Thus if a body is travelling at a constant speed in a circle, its velocity is constantly changing.

We know from Newton's first law that a body will retain its velocity unless another force acts upon it. Thus when a body travels in a circle a force must be applied to stop it from travelling in a straight line. This force is the centripetal force, the only force necessary for a circular motion. What is interpreted sometimes as a centrifugal force is the tendency of the object to follow in a straight line, which would bring it outside of its circular trajectory.

Physics teachers are keen to teach that the real force is Centripetal force and that centifugal force is the reactionary force which balances it. Conversion of angular momentum into linear momentum is used in a number of ways, the most obvious is perhaps a slingshot.

See also: Coriolis force, centrifugation