Centripetal Vs. Centrifugal

[Lu Zuckerman]

Dave Jackson posted a listing of explanations of centripetal and centrifugal forces made by various Scientists and much of it was beyond my limited comprehension. However there was one among several that justified the consideration of centrifugal force as a necessary force to balance out the mathematical equation. One of the explanations is provided below. You might note that he references a free body diagram which was a part of the response from Sikorsky when I posed my question to them regarding the use of centrifugal force in calculating loads on the rotorhead (centripetal force). One detractor indicated that the use of a free body diagram was an incorrect form in which to calculate these forces.

“In mechanics, when all forces and moments acting on a body are shown (i.e. the "free body diagram"), it is customary to use "inertia forces" to ensure equilibrium. An inertia force is a force equal and opposite to the net acceleration multiplied by the mass of the body. That is, it is equal and opposite of the external force acting on the body. For an object to move on a curved path, an acceleration directed towards the center of rotation is necessary (otherwise the object will maintain a straight-line path). This acceleration is one of the "normal" components of acceleration (the other normal component is the "coriolis" acceleration). The "centrifugal force" is the inertia force corresponding to this normal component of acceleration. It may be an imaginary force, if you like, - but an absolutely necessary one if the equilibrium equations are to be valid”.

Necip Berme, Ph.D. Professor, Mechanical Engineering The Ohio State University 206 W 18th Avenue Columbus OH 43210 Phone: [phone] Fax: [phone] E-mail: [email protected]

I would suggest that you all read the various descriptions of the two forces and you will see that there is a great deal of disagreement in the scientific community. Once reading those descriptions it will be abundantly clear why members of this forum including myself cannot agree on the same subject.