Round And Round We Go
 

Actually, the boy pulls on the rock (centripetal force) and the rock pulls on the boy (centrifugal force). The string is the medium through which these equilibrants do battle. :)

Thanks for replying yoda.

Ok. There's a hair which may need to be split depending on whether the string's mass can be ignored, but so far so good.

Are we agreed that centrifugal force does affect the boy but in no way affects the rock?

Sorry I fixed a typo there. The original said "any" where it now says "no".

While we are hair splitting - are they both equilbrants or is one a resultant?

Who's Your Daddy?
 

Actually, the rock is simply trying to move in a straight line. The centripetal string prevents it from doing so, and the apparent force -- from the rock's point of view -- is centrifugal.

No one ever hit a golf ball with terminology.
 

1-H (last paragraph) "As a term is specifically defined herein, that is the basic connotation which is always a dictionary definition but not necessarily that of Physics, Electrical, etc. The dictionary is generally considered a standard of precision. Scientific terms in quotes denote a loose application with obvious intent, because no better term seems available. Measurements given herein are for the golf course rather than the laboratory, but the laboratory will show them within acceptable tolerances. Clarity and usefulness are the only motive."

At the time of Homer Kelley's death in 1983, Merriam-Webster's New Collegiate Dictionary defined the following:

centrifugal force n: the force that tends to impel a thing or parts of a thing outward from the center of rotation

The String in TGM is the Longitudinal Center of Gravity or termed herein the Sweetspot Plane..I have a Training Aid with a String from the #3PP to directly to the CG of the head.....While Centrepetal force pulls it in a circle...Centrifugal force changes the length of this string...

What is the Longitudinal Center of Gravity?
 

The Golf Club's Longitudinal Center of Gravity is its Sweetspot (2-F). In other words, it is the Club's center of gravity when the Club is held lengthwise. It is neither the 'string' (the Left Arm and Clubshaft to which the Sweetspot is attached) nor the plane of motion (upon which the Sweetspot orbits).

Thanks for the clarification...

More definition,
 

The centripetal force-the action-is balanced by a reaction force, the centrifugal ("center-fleeing") force, which acts not on the circling object but on the source of centripetal force, usually located at the circle's center. The two forces are equal in magnitude and opposite in direction.

The Concise Columbia Encyclopedia is licensed from Columbia University Press. Copyright © 1995 by Columbia University Press. All rights reserved.

Interesting thread
 

Interesting thread- although it seems like no one can clearly define all the issues/perspectives involved in clearly understanding the topic at hand. Although, some may take that personally- it's more just an observation regarding the thread. And I'm certainly not one who necessarily could clearly define all the issues involved- in fact I'd probably be more off base than most.

Just one piece of the puzzle and confusion- and I could be wrong but in relation to Newton's third law- "action reaction" and the notion of "centripetal" and "centrifugal"- there seems to be some discussion of the boy, string, rock- and some of it appears to me to be on the wrong track.

Newton's third law to me - just says that you can't create a force out of nothing. To me it's similar or it's "sister" concept is that you can't create or lose Matter - it just is. So if you push a car down the street in a straight line- then the equal and opposite force is your feet on the ground pushing against the earth in the opposite direction of the motion of the car. That's a simple example of the action/reaction concept.

I would think the proper context of this in relation to the golf swing would be to look at the "whole system". So imagine that you have the clubhead or rock moving in a straight line- attached to it is a golf shaft or string- now to prevent that thing from moving is a straight line you give a tug on the shaft or string and it curves/moves toward the tugging- that's the centripetal force. So in relation to Newton's third law- you ask what offsets or allows that inward tug to happen? Depending on the movement- i.e. amount of force involved etc.- how heavy the rock is compared to the mover it could be different- but to me the basic reaction forces would be the feet pushing against the earth- that force is away from center and allows the force towards center to take place.

So I'm limiting my comment to the specific issue of action/reaction forces- and I don't see it - in the larger picture - being the boy and the string or the boy and the rock, or the rock and the boy.

Hope I didn't further clutter the post- with something that isn't clear.