Analysis of kinetic chain action in golf swing

[mandrin]

---I am guessing when you (essentially) say "don't fire hard through impact" you are saying that one should be making no extra effort to continuously turn?

---Ideally (at least for speed), the pivot comes to a dead stop correct? Assuming yes...ideally when?

---My feeling is that any decent athlete or good golfer should know this intuitively or at least be able to feel it/see it and relate to it.

birdie_man

---I hesitate answering these kind of questions as I realize science to be limpid and golf to be multi valued. As a general idea firing late leads to wasting energy not going to contribute to club head speed.

---Again, it is not so easy to have a definitive answer extrapolating from a simple math model to the immense complexity of a human golfer. I do not like to ascertain when not certain.

---Why then are only few doing it? It seems rather common the admonition: 'don't quit', indicating rather the fear of an early release and hence advice to keep firing.

 

[mandrin]

Beware; there is more than one "messenger" to shoot here as I have heard this same response given by others who were personally involved with Mr Kelley and thus got the same explanation first hand.

Indeed, golf lore of that time seemed to embrace the term centrifugal exclusively: almost as if no one had heard of the term centripetal, which is not far from the truth, I suspect.

Seems Mr Kelley was merely swimming with the tide rather than fighting it: yet you would ridicule him for that.

Then again, he is no longer around to defend himself so that is easy, eh!

You got it all dead wrong. I am not in any way belittling Homer Kelley. Only those who embellish history to suit their purpose. Some seem to seriously think that after Newton and Einstein there was Kelley.

The English scientists led by Dr Cochran, producing the study “Search for the “Perfect Swing” are happily using only the term centrifugal force.

Prof Jorgensen in his book ‘The Physics of Golf“ has no problem referring explicitly to centrifugal torque.

More recently, Dr Nesbit another reputable scientist, in his golf scientific papers, also refers to centrifugal torque.

Are you pretending that Homer Kelley, without formal scientific education, knew it better than reputable scientists but simpy played along, convinced that centrifugal did not exist but not wanting to hurt scientific consensus.

You really can’t be serious. There was no controversy about centrifugal force in his era. This is only very recent, primarily due to the huge amount of information available to all on the net.

So Burner, you therefore believe, re to centrifugal force, that

“Homer Kelley was fully aware that it did not really exist but simply adjusted to the normal usage. “

Burner, I am really disappointed. For a change I thought that I finally had something in common with Homer Kelley. i.e., both believing in the reality of centrifugal force, but now you are trying to take that nice feeling away from me. Shame on you, spoiling it all.

 

[mandrin]

British humour at its best

Hi Mandrin

Excellent stuff!! You are absolutely right about my rapid rate of learning in this matter! Actually, I've learned a hell of a lot since starting to interact with this forum - and not just about "fictitious" forces and I'm enjoying it enormously.

Firstly - an UNRESERVED APOLOGY for my disrespectful comments in earlier posts. Please disregard and, when I learn how, I'll delete/edit those bits.

Secondly - a HUGE THANK YOU for MAKING me get exposed to an area of physics that is so bloody interesting - I've been giggling since yesterday evening at the cleverness of the artificial contrivance of non-inertial frames in order to simplify calculation - so typical of physicists! Or are non-inertial frames artificial constructs?

OK - I haven't had a chance to consider your above post yet but I still have some questions and am very happy to let you guide my further education in these things.

Correct me if I'm wrong but are you saying that centrifugal force is real and not just a fictitious force created to explain phenomena in the artificial construct of a non-inertial frame? Where do I go to learn more about this?

In one of the threads, I read that the ideal way to apply force to the shaft is to pull from the top until the shaft is vertical (I assume this means angled to the plane when the left arm is parallel to the ground ish) and then to add force across the shaft. Do your data suggest otherwise, i.e., simply pull from the top and let it go?

Cheers

John (a humbled chemist - erm .... biochemist actually)

PS - if this does help my game are you going to insist that I swim all the way over there? Can I at least get the Mal out of the garage and paddle over?

John,

The reason why many physicists claim centrifugal force not to exist is really completely beyond me since it is so easy to demonstrate its existence, simple by measuring it as I have indicated. Looking for information in text books and on the web it quickly becomes obvious that there is frequently reference to centrifugal force as being a fictitious force with the usual notions about non inertial frames.

Yet rotating frames are only of concern to a very small group of scientists using it as a convenient tool to simplify things when dealing with complex problems. That is fine but than some really go overboard and also start denying the existence of centrifugal forces in inertial frames such as is considered normally to be the earth. A golfer and his golf swing don’t need in any way or form rotating reference frames for explanations.

Perhaps one possible reason for the ongoing confusion is perhaps too much emphasis in most text books on single particle physics and analyzing its behaviour in inertial and non inertial reference frames. Indeed for a single particle there is nowhere any need for centrifugal force, centripetal force will do. Centrifugal force then only appears as an fictitious force in non inertial reference frames.

But in real life there isn’t anything which can be considered isolated as a single particle. ALL that exists interacts with other things. For instance a golfer is a bunch of bony masses interacting through various types of joints. Therefore single particle physic is perhaps cute as a starter but is in no way representing physical reality.

Reality is about interaction of multiple bodies in a wide variety of ways. Kinetic chain is typically a concept reflecting such reality. And when one deals with interaction one deals automatically with action reaction force pairs and hence indeed the centrifugal centripetal action reaction force pair.

To put above in a nutshell.

Many scientists/laymen limit their view narrowly to Newton’s first and second law. These two laws are strictly concerned with single particles. To explain away claims about centrifugal force they are forced to argue esoterically that it is simply some inherent property of inertia.

However as soon as one accepts interaction of particles/bodies, hence reflecting the reality as all around us, then one can apply Newton’s third law and henceforth simply and logically explain very easily the real existence of centrifugal force.

Again, just out of interest (honestly!!!), how did you arrive at the data? Is it purely mathematical modelling, i.e., paper based? Did you use simulation software? Is there any back up from actual Iron Byron machine measurements?

John, I thought it to be self evident from my post. I use a mathematical model. I don’t think that the four input torques used look that they have been taken from real gofers. This is indeed a definite advantage of math models. One can ‘experiment’ anything one wants and quickly show trends or effects of large variations of input and/or system parameters.

PS I don't think that swimming is such a good idea. I suggest that you try to lure Brian over to your side of the ocean. As far as I know he usually travels by air it will be quicker and safer for all concerned.

 

[matt kluck]

Good Post!

Dear Mandrin,
It is good of you to bring to the board the realm in which psuedo forces are used. as well as how they relate to rotating frames. Math models are great aren't they.
Best in golf and educating the masses,
MK

 

[mandrin]

Dear Mandrin,
It is good of you to bring to the board the realm in which psuedo forces are used. as well as how they relate to rotating frames. Math models are great aren't they.
Best in golf and educating the masses,
MK

Matt,

Thanks for your appreciation. I am glad that you share the same enthusiasm for math models, so malleable and so interesting for doing trend studies and the like. Educating the masses, I am not so sure. But it is fun trying.

 

[matt kluck]

Educatng the Masses

Mandrin,
Improbable at best but fun trying! Math is endless and adaptable, the universal language to which most misapply because of the malleable aspects. I look forward to your continued contributions to the forum and perhaps meeting someday to engage in some meaningful conversation. Some of the best information I read is a result of the topics you post and my indulgence in learning from those posts. To the best and continued success to educating the masses.
MK

 

[mandrin]

Hi Mandrin

Correct me if I'm wrong but are you saying that centrifugal force is real and not just a fictitious force created to explain phenomena in the artificial construct of a non-inertial frame? Where do I go to learn more about this?

Probably on the internet but not in Physics

pseudo force: Definition from Answers.com

golfspike,

Yes, correct, centrifugal force is very real and omnipresent. Centrifugal force is however also used in non-inertial frames as a fictitious force to be able to apply Newton’s laws. However, this ambiguous double use is not usually pointed out to the poor laymen who googles for some information on the subject. Frequently it is simply defined as a fictitious force and emphasized that only centripetal force is real. Take for instance, just one typical example, the web site h2g2. It states unequivocally that centrifugal force does not exist at all. The poor confused golfer however in all of golf literature reads only about subjects such as centrifugal force swing and the like.

How come that if one introduces the word ‘centrifugal’ Google suggests:

centrifugal clutch
centrifugal governor
centrifugal pump
centrifugal compressor
centrifugal fan
centrifugal supercharger
centrifugal casting
centrifugal blower
centrifugal chiller

Interestingly, introduce ‘centripetal’ and Google comes around with not even a single suggestion.

This reflects the world of engineers who are more connected to reality. However, even scientists have some common sense. Search for ‘centrifugal stiffening’ and plenty of titles of scientific papers appear on the screen with ‘centrifugal stiffening‘. Do the same with ’centripetal stiffening’ and barely a few are presented. Seeing this dichotomy is indeed rather bewildering. It almost feels like some political or religious kind of thing where common sense has been evacuated. For instance, a pseudo-scientist like nmgolfer goes around on various golf forums ridiculing anyone who even modestly suggests that centrifugal force is for real. The reaction of some when they hear the term 'centrifugal force’ is perhaps amusing but also rather irrational and on the verge of paranoia.

It basically boils down to a clear dichotomy in vision. A realistic view is to acknowledge the interactions as they occur everywhere between bodies and henceforth centrifugal forces impose themselves immediately as normal and logic. But usually one analyzes such typical examples as roller coasters, centrifuges or turning cars as if there is a single particle/body involved, mystifying with some additional doodling around with non inertial reference frames, and guaranteed, almost everyone is either totally confused or quite impressed by all this show off of mathematics and convinced that science must be right, and that this darned centrifugal force to be a diabolic invention by people like mandrin.

 

[johnpritch]

Hey Brian / Mandrin

Brian

As I sit here in sunny Wales, still smarting from Ronan O'Gara's drop-goal in the dying minutes to deny us the triple crown yesterday (Ireland won the Grand Slam - defeating the other 5 nations in the 6-Nations championship) I urge you not to kick Bronco Billy off the forum because you think he and I may be one and the same!! While that would probably be a considerable compliment to me, it is not so - I doubt that Billy would realise that rugby football is the divine game that you lot ruined by putting helmets on the players and using a little pointy ball, etc.. I find that I do like Billy because (a) I had a Bronco Billy outfit when I was little and it brings back lovely memories of playing cowboys and .. erm native americans (b) I think he brings a little colour to the forum (ouch - sorry, Billy) and (c) he's prepared to offer support to transatlantic travellers, albeit at the right price!

I got into this argument for the following reasons:

1. I honestly thought that Mandrin's data had important implications for the golf swing, if the data could be validated.
2. I thought he was perpetuating a misconception - the existence of centrifugal force - I seriously underestimated his intellect, mainly due to his conclusion that golfers muscle the ball because science teachers deny the existence of centrifugal force - it seems to me that everyone realises from their everyday experiences that moving masses can produce effective collisions, especially if the mass is large (big lorry) or the velocity is high (speeding bullet), with no need to add something just before impact.

Mandrin

Thanks for posting an explanation that I could follow!! I though you might start invoking General Relativity or something. I can see you have a much better command of Newtonian mechanics than I. My previous fumblings are my own. When I mentioned the Cambridge Uni guys' support, it was simply for the non-existence of centrifugal force - btw, one had a first in theoretical phys 35 years ago - so he didn't sleep through too many lectures!! My former chemistry students would have a good laugh at my attempts to make sense of phys.. In 32 years of teaching in secondary schools in areas with a high index of social deprivation, the examination results consistently exceeded the predictions based on prior attainment indicators - and we had a good giggle along the way. Above all else, I hope I managed to instill into them the notion that data must be scrutinised before being accepted, no matter the source and that knowing your 2,4-dinitrophenylhydrazine from your napthalen-2-ol is a secondary consideration.

I still wonder why the accepted view in the world of physics, populated as it is by the brightest of minds, is that centrifugal force is a fictitious force. The use of the term does not impute any reality to it. For example, a brilliant teacher once used the term "shake the sugar" in an instructional video - I didn't see any sugar actually being shaken but I got the idea. OK - maybe that analogy is a bit dodgy. Here's one from the world of chem - I loved Linus Pauling's ideas on hybridisation of atomic and molecular orbitals - explained so many things so well. A gentleman who was formerly Reader at Cardiff Uni told me that developments in photo-electron microscopy had thrown doubt onto the validity of those ideas. It's like being told that my much-loved Springer Spaniel puppy is a phantasm! In a sense, all concepts are mental constructs that point to a reality (Zen's finger pointing at the moon, etc.). As you are all too aware, scientists freely use artificial constructs to obtain an end and physicists are particularly clever at that.
I've read through your explanation and have the following thoughts - be gentle with me now - I'm in a fragile state (points difference means we finished 4th in the table!!).

Firstly, we need something to set the gizmo moving. Could be a torque at the hub or an impact on the tube (couldn't help giggling again at the frictionless surface and the frictionless tube - typical physicist - Darling, how much do you love me? 93.64% to four significant figures!). Let's imagine an impact on the stationary tube at right angles to the tube and through the centre of the mass. Due to its inertia, the mass responds to this impact by "trying" to move in the direction of the force on it - this is at a tangent to our circle. As soon as this impulse, Ft, displaces the tube from it's start position, there will be a component resolvable into a direction along the spring. The poor spring, by definition, is extensible and this component is able to overcome the forces of attraction between the positive ions and the surrounding delocalised electrons in the metal. So the spring's extension is due to the effect of this initial impact.
Further, once the mean separation of the positive ions has resulted in the mutual repulsion between the positve ions decreasing below the value of the attraction between them and the delocalised electrons, the spring will shorten a bit until that repulsion becomes greater than the attraction etc, etc. Thus, an oscillating system will result until internal friction dampens it. So for some time this mass isn't going to move in anything like a circle. Why don't we go the whole hog and imagine a frictionless pivot!!!! I think the initial impact causes a continual acceleration so that the spring stretches beyong its elastic limit, snaps and the marble shoots outta that shaft!! Discuss!

Yours RESPECTFULLY,

John

 

[Bronco Billy]

This and All Universes are Pseudo Constructs of the Human Mind....

Mandrin

Thanks for posting an explanation that I could follow!! I though you might start invoking General Relativity or something. I can see you have a much better command of Newtonian mechanics than I. My previous fumblings are my own. When I mentioned the Cambridge Uni guys' support, it was simply for the non-existence of centrifugal force - btw, one had a first in theoretical phys 35 years ago - so he didn't sleep through too many lectures!! My former chemistry students would have a good laugh at my attempts to make sense of phys.. In 32 years of teaching in secondary schools in areas with a high index of social deprivation, the examination results consistently exceeded the predictions based on prior attainment indicators - and we had a good giggle along the way. Above all else, I hope I managed to instill into them the notion that data must be scrutinised before being accepted, no matter the source and that knowing your 2,4-dinitrophenylhydrazine from your napthalen-2-ol is a secondary consideration.

I still wonder why the accepted view in the world of physics, populated as it is by the brightest of minds, is that centrifugal force is a fictitious force. The use of the term does not impute any reality to it. For example, a brilliant teacher once used the term "shake the sugar" in an instructional video - I didn't see any sugar actually being shaken but I got the idea. OK - maybe that analogy is a bit dodgy. Here's one from the world of chem - I loved Linus Pauling's ideas on hybridisation of atomic and molecular orbitals - explained so many things so well. A gentleman who was formerly Reader at Cardiff Uni told me that developments in photo-electron microscopy had thrown doubt onto the validity of those ideas. It's like being told that my much-loved Springer Spaniel puppy is a phantasm! In a sense, all concepts are mental constructs that point to a reality (Zen's finger pointing at the moon, etc.). As you are all too aware, scientists freely use artificial constructs to obtain an end and physicists are particularly clever at that.
I've read through your explanation and have the following thoughts - be gentle with me now - I'm in a fragile state (points difference means we finished 4th in the table!!).

Firstly, we need something to set the gizmo moving. Could be a torque at the hub or an impact on the tube (couldn't help giggling again at the frictionless surface and the frictionless tube - typical physicist - Darling, how much do you love me? 93.64% to four significant figures!). Let's imagine an impact on the stationary tube at right angles to the tube and through the centre of the mass. Due to its inertia, the mass responds to this impact by "trying" to move in the direction of the force on it - this is at a tangent to our circle. As soon as this impulse, Ft, displaces the tube from it's start position, there will be a component resolvable into a direction along the spring. The poor spring, by definition, is extensible and this component is able to overcome the forces of attraction between the positive ions and the surrounding delocalised electrons in the metal. So the spring's extension is due to the effect of this initial impact.
Further, once the mean separation of the positive ions has resulted in the mutual repulsion between the positve ions decreasing below the value of the attraction between them and the delocalised electrons, the spring will shorten a bit until that repulsion becomes greater than the attraction etc, etc. Thus, an oscillating system will result until internal friction dampens it. So for some time this mass isn't going to move in anything like a circle. Why don't we go the whole hog and imagine a frictionless pivot!!!! I think the initial impact causes a continual acceleration so that the spring stretches beyong its elastic limit, snaps and the marble shoots outta that shaft!! Discuss!

Yours RESPECTFULLY,

John

.

 

[johnpritch]

Hey Billy

Is this the multiple universe idea postulated by quantum mechanics?

Seriously though, I agree with you.

Losing to the Irish still hurts!

 

[mandrin]

Mandrin

Thanks for posting an explanation that I could follow!! I though you might start invoking General Relativity or something. I can see you have a much better command of Newtonian mechanics than I. My previous fumblings are my own. When I mentioned the Cambridge Uni guys' support, it was simply for the non-existence of centrifugal force - btw, one had a first in theoretical phys 35 years ago - so he didn't sleep through too many lectures!! My former chemistry students would have a good laugh at my attempts to make sense of phys.. In 32 years of teaching in secondary schools in areas with a high index of social deprivation, the examination results consistently exceeded the predictions based on prior attainment indicators - and we had a good giggle along the way. Above all else, I hope I managed to instill into them the notion that data must be scrutinised before being accepted, no matter the source and that knowing your 2,4-dinitrophenylhydrazine from your napthalen-2-ol is a secondary consideration.

I still wonder why the accepted view in the world of physics, populated as it is by the brightest of minds, is that centrifugal force is a fictitious force. The use of the term does not impute any reality to it. For example, a brilliant teacher once used the term "shake the sugar" in an instructional video - I didn't see any sugar actually being shaken but I got the idea. OK - maybe that analogy is a bit dodgy. Here's one from the world of chem - I loved Linus Pauling's ideas on hybridisation of atomic and molecular orbitals - explained so many things so well. A gentleman who was formerly Reader at Cardiff Uni told me that developments in photo-electron microscopy had thrown doubt onto the validity of those ideas. It's like being told that my much-loved Springer Spaniel puppy is a phantasm! In a sense, all concepts are mental constructs that point to a reality (Zen's finger pointing at the moon, etc.). As you are all too aware, scientists freely use artificial constructs to obtain an end and physicists are particularly clever at that.
I've read through your explanation and have the following thoughts - be gentle with me now - I'm in a fragile state (points difference means we finished 4th in the table!!).

Firstly, we need something to set the gizmo moving. Could be a torque at the hub or an impact on the tube (couldn't help giggling again at the frictionless surface and the frictionless tube - typical physicist - Darling, how much do you love me? 93.64% to four significant figures!). Let's imagine an impact on the stationary tube at right angles to the tube and through the centre of the mass. Due to its inertia, the mass responds to this impact by "trying" to move in the direction of the force on it - this is at a tangent to our circle. As soon as this impulse, Ft, displaces the tube from it's start position, there will be a component resolvable into a direction along the spring. The poor spring, by definition, is extensible and this component is able to overcome the forces of attraction between the positive ions and the surrounding delocalised electrons in the metal. So the spring's extension is due to the effect of this initial impact.
Further, once the mean separation of the positive ions has resulted in the mutual repulsion between the positve ions decreasing below the value of the attraction between them and the delocalised electrons, the spring will shorten a bit until that repulsion becomes greater than the attraction etc, etc. Thus, an oscillating system will result until internal friction dampens it. So for some time this mass isn't going to move in anything like a circle. Why don't we go the whole hog and imagine a frictionless pivot!!!! I think the initial impact causes a continual acceleration so that the spring stretches beyong its elastic limit, snaps and the marble shoots outta that shaft!! Discuss!

Yours RESPECTFULLY,

John

John,


The scenario you depict is something I have analyzed in the past albeit with a slightly different scenario, see Figure.

​

The mass m is moving with a constant velocity V from a to b and arriving at b adheres instantly at one end of an elastic cord at its neutral length, with the other end fixed at the center of rotation O. There is small amount of damping incorporated into the elastic cord. Gravity is ignored so motion occurs horizontally on a table with zero friction.

Initially there is quite some action. The mass m dislikes profoundly being hampered in its motions but more it generates centrifugal force, trying to escape, more the elastic band fights back with its centripetal force. The mass m realizes quickly that all rebellion is vain and after some quick and intensive tug of war negotiations settles for a durable dynamic peace.

 

[johnpritch]

Mandrin

If that mass is anything like my Springer Spaniel pup it'll be constantly monitoring that elastic cord for any sign of weakness in order to break free!

I'm all for a durable peace!!!

Still not convinced but thanks for your ideas and the discussion has made me realise that I was just prepared to trot out educational dogma without investigating it properly for myself! To be honest, I haven't yet had a convincing proof of the non-existence of centrifugal force either! I'll keep looking into it until I resolve it for myself though.

Take care and keep the inputs into the forum coming - everyone seems to appreciate them so much and I can now see why.

John

 

[mandrin]

Mandrin

If that mass is anything like my Springer Spaniel pup it'll be constantly monitoring that elastic cord for any sign of weakness in order to break free!

I'm all for a durable peace!!!

Still not convinced but thanks for your ideas and the discussion has made me realise that I was just prepared to trot out educational dogma without investigating it properly for myself! To be honest, I haven't yet had a convincing proof of the non-existence of centrifugal force either! I'll keep looking into it until I resolve it for myself though.

Take care and keep the inputs into the forum coming - everyone seems to appreciate them so much and I can now see why.

John

……..…..
As I said, I have no problem with the validity of the kinetic chain snap idea but as a lifelong science teacher doing one's utmost to undo popular misconceptions, it's hard to stand by and allow them to be perpetrated without comment.

John,

It took thousands of years involving great spirits such as Aristotle, Buridan, Galileo, Descartes, Huygens, Gassendi, Newton, d’Alembert, and many others to arrive at the modern scientific concept of inertial motion and yet there is still the present confusion. Considering furthermore that Newton’s laws are effectively based on a circular definition using laws and coordinate systems to define each other in turn and seeing you refer to a lifetime of vigilance defending against popular misconceptions and nevertheless admitting not being aware of the confusion re to centrifugal force as a science teacher, I am convinced that you will have enough food for thought for yet another lifespan. However, since what goes around comes around we will surely discuss exactly the same matter in some future existence. Happy teaching and golfing meanwhile.