The discussion has moved on Mathew.

If you want to contribute, you might start by looking at yoda's posts and my responses. Numerous other people are also making strong contributions, and yoda and everybody else appear to have immediately understood what I'm here to discuss. I'm enjoying my time here immensely.

Firstly it is not your place to tell me what conditions I can contribute to. Secondly we are still on this subject.....centrifugal force.... just tell me where he said "centrifugal powered".

Looking forward .... as in you in comparison to Homer - are you a comedian....

Quite right! You'll notice that I edited my post to include the words "might like". I did this whilst you were replying and completed the edit after your reply. It's your choice Mathew. You must decide what your contribution is to be. I'm here to discuss physics.

No kidding - I thought it was to discuss the weather:eyes:

Perhaps you can again reference the quote from the golfing machine that says "centrifugal powered" that I pointed out with "snideness".

I can't argue beyond this explanation. In the case of the TGM model the string length (radius) is from shoulder the clubhead and it lengthens dramatically from start down to impact. Like a flail with the wrist as the thong.

Is this close to correct? No physics degree over here,,

CW

Yes. The flail model is an essential element of any model of the golf swing. I hope to move on to discussion of the flail and the throw out effect fairly shortly. The only unresolved issue I see with the stone and the rock is the "frame of reference" problem yoda raised. After that it's full steam ahead.

The Frame of Reference is a Choice
 

The frame of reference is always a choice. The laws of physics in this case are invariant regardless of frame of reference. However, the explanation of what is going on varies. A rotating reference frame is proper during the downswing since that is the frame of reference the golfer lives in so to speak. You wish to keep things in a non-rotating reference frame because it makes the centrifugal force explanation less applicable.

This whole argument is splitting hairs about reference frames and centrifugal force. It is pointless to the golfer. One will get the right answer whether one invokes the concept of centrifugal force or explains the phenomena as inertial resistance of the clubhead mass. Basically it all comes down to what folks will understand more easily. Centrifugal force explanations are more intuitive to understand for the majority than inertia which is why it is more generally taught that way in universities across the world (to physicists). It is nice that you learned your physics a different way, but the answers all turn out the same. I suspect we will just have to agree to diagree, Jack.

Ok. Let's try that assertion out with a question. Why in the frame of reference of the rock does the centrifugal force act on the rock when in an inertial frame the centrifugal force acts on the boy?

A non-inertial frame of reference changes everything. Forces appear like the ones which the camera on the rock shows affecting the trees and the grass. It becomes a mess. The simple reason I wish to keep things in a non-rotating reference frame is because physics in a rotating frame is so complicated, but will after a lot of hard work provide the same answers (for the ball) as in an inertial frame.

Newton's law that "an object at rest will remain at rest unless a resultant force is applied" becomes "an object at rest will only remain at rest if a centripetal force is applied". See what I mean?

I have no problem if you wish to disagree, but be so kind as to point out the error in what I say rather than discussing motives and making condecending remarks like "it's nice that you learned your physics in a different way".

I will, however, be very interested in reading your explanation of the physics of the throw out effect in a non-inertial frame of reference if you want to discuss it.

Communication issues
 

Golf Sceptic- Just my perspective but it appears to me- that you have a significant communication problem. Don't know if you are aware of it or not. I don't say that in a derogatory tone or sarcastic tone- it's just the feedback I would give you - in order to improve your performance in the future. I'm assuming you know your subject but can't communicate it clearly. You've got 25 somewhat extensive posts on this thread/subject matter and it's my feeling that no one (at least myself) has made any progress in understanding your perspective or the context and importance of your point. Every new post doesn't get you any closer to the answer than the previous post.

My only guess to the problem is that the foundation of concepts that supports your viewpoint - that seems obvious to you is not obvious to your audience (me). When you build a concept, idea, system, theory- you can't get to the theory and take everything as self-evident- especially for teaching or describing it's functioning- you've got to essentially retrace the original route - in principle- not point by point- to it's basis- starting reference points- those things that you can see, touch, smell, hear. Homer had a similar problem- so you've got company. You've also got to understand when you mention any particular point- how other people might mis-interpret it and explain and what the wrong turns could be at any turn- so that you keep the reader on track.

So that's why very few people stuck it out with Homer- and very few will stick it out with you- (like me)- so when you ask "This is where the man on scales in lift will help if you need more detail." I'm thinking no thanks- because that post is going to be like the last 25 - not going to get me any closer to you answering and me understanding whatever you were talking about when this thread started.

That's just my feedback- hope it helps you.

Thanks Mike, I take your comments in the generous spirit in which you sent them.

Ok. Here's the gist of it. I'm interested in the physics underlying TGM. In essential terms my proposition is that centrifugal force does not cause the throw out effect.

This requires a very precise discussion of the physics. The discussion is not for everybody, requires either training or an inquiring mind and great patience, will only generate fresh insights for the very few, and will interest even fewer.

Now. ThinkingPlus has two physics degrees I believe, and physics is her job. Me too, except that I am now retired and I focussed on Pure and Applied Mathematics in my undergraduate days. Unfortunately, when she took me to task about frames of reference, it takes the discussion to a whole new level of abstraction. I had hoped not to have that discussion, but yoda made it necessary and stephanie put it centre stage.

ThinkingPlus, by the way, has given me an insight into why Mr Kelley may (I emphasize may) have explained centrifugal force in the way he did.

Quite right. We all know that my proposition is that centrifugal force does not cause the throw out effect. We've done the boy and the rock to illustrate what is really happening in a simple situation involving centrifugal force (and taken a few side trips). Unless ThinkingPlus wants to discuss physics in non-inertial frames of reference, or anybody else wants to clarify any other issues, I'm ready to state my case.