Reactive centrifugal force

[3][4][5][6] The figure at right shows a ball in uniform circular motion held to its path by a string tied to an immovable post.

In this system a centripetal force upon the ball provided by the string maintains the circular motion, and the reaction to it, which some refer to as the reactive centrifugal force, acts upon the string and the post.

Newton's first law requires that any body moving along any path other than a straight line be subject to a net non-zero force, and the free body diagram shows the force upon the ball (center panel) exerted by the string to maintain the ball in its circular motion.

An example of this kind of engineering concept is an analysis of the stresses within a rapidly rotating turbine blade.

A centrifugal clutch is used in small engine-powered devices such as chain saws, go-karts and model helicopters.

At higher speeds, when the shoes can't move any further out to increase the spring tension, due to the outer drum, the drum provides some of the centripetal force that keeps the shoes moving in a circular path.

This distinguishes it from the inertial or fictitious centrifugal force, which appears only in rotating frames.

A ball in circular motion held by a string tied to a fixed post.
A two-shoe centrifugal clutch . The motor spins the input shaft that makes the shoes go around, and the outer drum (removed) turns the output power shaft.