A look at various pivot torques

[Brian Manzella]

NEWSFLASH FROM THE REAL WORLD!

Ping had a picture they gave to accounts back in the day. I saw it many times.

The picture was a STROBE PIC and the hands slowed down.

Ha!

 

[mandrin]

Mandrin - I agree with you. Your mathematical model doesn't produce a good club release pattern.

You seemingly believe, with a great deal of certainty, that your mathematical model accurately predicts reality. I, however, disagree - because I think that many PGA tour players (like Tiger Woods) have a downswing arm/hand action that starts with a steady acceleration and then has a constant, or near-constant, velocity through most of the remainder of the swing (even if the hands slows down 0.03 seconds prior to impact). Your model predicts that those PGA tour players should have a club release that is already complete by the 10 o'clock position (arm and clubshaft are in a straight line). Why?

I personally believe that your model's predictive ability regarding the release phenomenon is very poor - with respect to "real" golf swings. Am I right or wrong? Surely, the answer depends on the biomechanical principles underlying your mathematical model's calculations. So, again, I request the following information.

1) There is one independent variable (speed of the central arm) and one dependent variable (speed of the peripheral arm/club). The cause-and-effect relationship between the independent variable and the dependent variable must be defined by a set of mechanical/physical principles. What is the fundamental principle of the force acting at the peripheral hinge point?

Is that force acting on the grip end of the club as a linear force pulling at a passive free-hinge point? Is your mathematical calculations similar to nmgolfer's explanation, and if not, why not?

2) Will the predicted release phenomenon be different for the following three scenarios - i) the peripheral lever is made of a homogenous material where the COG of the peripheral arm is at the center of the arm, ii) the peripheral arm is made of a heterogenous material and where the COG is near the far end of the peripheral arm, iii) the peripheral arm is made of heterogenous material and where the COG is near the near end of the peripheral arm?

You state that I am "shuffling my cards" implying that I am not being clearly forthright about my own position. I may certainly be wrong - but I have stated my position as clearly as I can, and I have divulged my thinking/assumptions as clearly/lucidly as I can accomplish that goal. Now it is your turn to divulge all the assumptions/principles underlying your mathematical model, so that forum members can independently judge the likely legitimacy of your mathematical modelling without being predjudiced by my personal opinions.

Jeff.

JeffMann,

I am really stunned by your dog like persistence. It reminds me of an advertisement of a certain battery which keeps going and going and going. But enough is enough. There is seemingly no end to it and we will end up me having the prove hat God is the final cause of it all.

Let me just briefly summarize, but that will be the last I will say about it. After that I will leave with your ideas, since they are seemingly poured in extremely tough concrete.

Newton’s second law for a single particle can be extended to multiple bodies having both translational and rotational motion.

There are various methods to do so, such as Newton-Euler approach, Lagrangian method, Kane’s equations, Hamilton’s equations, Hamilton’ principle, TMT approach.

Notwithstanding the method chosen they all derive the dynamic equations for a system of rigid bodies undergoing both translational and rotational motion.

These equations are really rather complicated extensions of Newton’s second law for a single particle, even if in the final formulation this is not evident.

I use these several of these well proven, universally accepted methods, being taught in every corner of the globe.

I don’t think that your ideas will improve on these theories developed and nourished by a large number of scientists over a considerable period of time.

I don’t want to refer to the ideas of your favorite scientist with his ‘unique’ view on things, other than to say that you have been largely inspired by them with seemingly little success.

He has had enough excitement, just recently, and for a couple of hours it has been nice and quite on the forum. Let's enjoy it for so long as it lasts.

 

[JeffM]

Brian

At what point in the downswing did the PingMan's peripheral hinge joint (hands) slow down?

Jeff.

 

[mandrin]

Could you explain this verbally? It seems counterintuitive that the club would catch up to the arm so early if the arm is in a constant state of acceleration. Also, explain verbally how to keep the club from catching up prematurely, as it relates to acceleration?

Bigwill,

Please, don’t make the mistake to take the figure to represent a real golf swing as it is only meant to be a mathematical translation of JeffMann’s ideas, largely inspired by nmgolfer’s website information. Clearly it is not making these ideas to appear very healthy.

In a down swing there is first a negative torque, trying to back-knife the club. About 0.1 sec into the down swing this torque changes in sign and is then subsequently trying to open the angle. The initial negative torque however strives to keep the angle when starting the downswing from the top.

 

[JeffM]

Mandrin

This series of statements is essentially your answer to my VERY SPECIFIC questions-:

"Newton’s second law for a single particle can be extended to multiple bodies having both translational and rotational motion.

There are various methods to do so, such as Newton-Euler approach, Lagrangian method, Kane’s equations, Hamilton’s equations, Hamilton’ principle, TMT approach.

Notwithstanding the method chosen they all derive the dynamic equations for a system of rigid bodies undergoing both translational and rotational motion.

These equations are really rather complicated extensions of Newton’s second law for a single particle, even if in the final formulation this is not evident.

I use these several of these well proven, universally accepted methods, being taught in every corner of the globe."

--------------------------------------------------------------

Every neutral forum member should easily understand what your "answer" represents - a "cop-out".

I think we all show how we think and rationalise when we make statements in this forum. I am not at all surprised that you cannot deal with my pointed questions, considering that you also have the following set of irrational beliefs.

"When hitting a golf ball, energy is trasferred from the impacted ball, back through the club and arms, and that energy causes the right shoulder to temporarily slow down".

Jeff.

 

[daniell]

I think we all show how we think and rationalise when we make statements in this forum. I am not at all surprised that you cannot deal with my pointed questions, considering that you also have the following set of irrational beliefs.

"When hitting a golf ball, energy is trasferred from the impacted ball, back through the club and arms, and that energy causes the right shoulder to temporarily slow down".

Jeff.

ehh Mandrin, I think it is irrational too if you did actually made those statements.

I will believe the doctor on this one .

No offense.

 

[Bigwill]

Bigwill,

Please, don’t make the mistake to take the figure to represent a real golf swing as it is only meant to be a mathematical translation of JeffMann’s ideas, largely inspired by nmgolfer’s website information. Clearly it is not making these ideas to appear very healthy.

In a down swing there is first a negative torque, trying to back-knife the club. About 0.1 sec into the down swing this torque changes in sign and is then subsequently trying to open the angle. The initial negative torque however strives to keep the angle when starting the downswing from the top.

Ok, so is acceleration or rate of acceleration causing the negative torque you spoke on above? If not, what causes that negative torque?

 

[Bronco Billy]

Hi There

Mandrin's Model DID Demonstrate ONE Thing in both Cases- Jeffs and Mine.....The Club RELEASED WITHOUT The Arm SLOWING Down..... It Seems to Me the Model Could be Tweaked(Shifted in Phase etc.) to more Represent a Real Golf Swing.... Jeff-Did We Win After All?????

Cheers

 

[mandrin]

Jeff-Did We Win After All?????

Cheers

Bronco Billy,

If it is simply a matter of winning or losing than I am clearly wasting my time. For every question quickly formulated I spent often considerable time to come up with an answer.

There is no fun to have to drag resisting bodies single handed up stream. So perhaps I should consider simply to let go and travel more lightly.

 

[Bronco Billy]

Bronco Billy,

If it is simply a matter of winning or losing than I am clearly wasting my time. For every question quickly formulated I spent often considerable time to come up with an answer.

There is no fun to have to drag resisting bodies single handed up stream. So perhaps I should consider simply to let go and travel more lightly.

Hi Mandrin

Didn't Mean to Piss you Off or Call You the Enemy.... Ease Up.. Without You, Your Models, nm, Others, etc. I would not be Where I'm In trying to Understand what the Hell is Going on in the Golf Swing.... I for One Greatly Appreciate Your Efforts..... Have a Good Day .....

Cheers

 

[JeffM]

Mandrin wrote-: "If it is simply a matter of winning or losing than I am clearly wasting my time. For every question quickly formulated I spent often considerable time to come up with an answer."

I tend to agree with mandrin that this is not an issue of winning or losing. It is a matter of our MUTUAL effort-interaction as we all try to best understand the biomechanics of the golf swing by offering suggested solutions. His contribution is therefore valuable.

I personally think that mandrin has done himself a great disservice by keeping the mechanical/physical principles underpinning his mathematical analysis cryptic/hidden. I think that mathematical analysis is a valid tool, but only if the underlyling assumptions are expressed forthrightly and if the underlying assumptions are factually, and logically, sound. There is also the important issue of result-plausability - are the results of the mathematical analysis plausible from a common-sense perspective. Mandrin's diagrams for the release pheneomenon (especially for a steady, early arm/hand acceleration and subsequent constant velocity arm/hand swing) are totally implausible. Using simple common-sense, one cannot even begin to believe that club release will be complete by 10 o'clock - when that arm/hand swing pattern is probably the most frequent pattern used by PGA tour players.

I actually regard the issue of whether the hands slow down just prior to impact a very minor issue - because the release phenomenon starts well before that time. Therefore, there cannot be a cause-and-effect relationship between the "hand slowing" and the "release". David Hume, the British philospoher, wrote extensively on cause-and-effect relationships, and one of his basic principles is that a "cause" must have a contiguous relationship to an "effect" from a time perspective, and a "cause" must always precede the "effect". If the release phenomenon precedes ANY hand slowing (that occurs very late in the downswing), then it is impossible for the hand slowing to be causing the release. It is certainly possible that the release is causing the hand slowing, but further analysis would be needed to establish an air-tight cause-and-effect relationship.

Another interesting point is that the release occurred in mandrin's mathematical models even if there is no arm/hand slowing. That "fact" in itself demonstrates that the release phenomenon cannot be causally related to arm/hand slowing.

I still think that nmgolfer's explanation is the best explanation offered for the release phenomenon, although I remain open to alternative theories. His explanation certainly fulfills the criteria for Occam's razor (when two explanations predict an event, then the simpler explanation should be preferred). nmgolfer's explanation is simpler because the SAME explanation applies to the PingMan machine (which has a constant arm velocity with no proven slowing down prior to impact) and a PGA tour golfer's swing (which eiither has a steady hand acceleration pattern throughout the downswing, or a steady acceleration in the early downswing followed by a near-constant velocity in the mid/late downswing - both patterns probably associated with hand slowing just prior to impact).

Jeff.

 

[mandrin]

Mandrin

This series of statements is essentially your answer to my VERY SPECIFIC questions-:

"Newton’s second law for a single particle can be extended to multiple bodies having both translational and rotational motion.

There are various methods to do so, such as Newton-Euler approach, Lagrangian method, Kane’s equations, Hamilton’s equations, Hamilton’ principle, TMT approach.

Notwithstanding the method chosen they all derive the dynamic equations for a system of rigid bodies undergoing both translational and rotational motion.

These equations are really rather complicated extensions of Newton’s second law for a single particle, even if in the final formulation this is not evident.

I use these several of these well proven, universally accepted methods, being taught in every corner of the globe."

--------------------------------------------------------------

Every neutral forum member should easily understand what your "answer" represents - a "cop-out".

I think we all show how we think and rationalise when we make statements in this forum. I am not at all surprised that you cannot deal with my pointed questions, considering that you also have the following set of irrational beliefs.

"When hitting a golf ball, energy is trasferred from the impacted ball, back through the club and arms, and that energy causes the right shoulder to temporarily slow down".

Jeff.

Jeffmann,

I am trying very hard to remain polite since you seem immensely naïve, but sincere; however with barely a minimum grasp of scientific notions.

I like to explain, even if it takes lots of time, but there has to be a minimum of pleasure in it for me too.

(please, supply link to quote)

 

[Bronco Billy]

I still think that nmgolfer's explanation is the best explanation offered for the release phenomenon, although I remain open to alternative theories. His explanation certainly fulfills the criteria for Occam's razor (when two explanations predict an event, then the simpler explanation should be preferred). nmgolfer's explanation is simpler because the SAME explanation applies to the PingMan machine (which has a constant arm velocity with no proven slowing down prior to impact) and a PGA tour golfer's swing (which eiither has a steady hand acceleration pattern throughout the downswing, or a steady acceleration in the early downswing followed by a near-constant velocity in the mid/late downswing - both patterns probably associated with hand slowing just prior to impact).

Hi Jeff

Man You Sure as Hell are Writing Differently these Days.... Hey Dude You went from wanting Kindergarten Explanations to Quoting Great Philosophers, etc. in about two Weeks?????

I'm Bettin nm's Theories and Mandrin's Model are in Mathematical Agreement.... They Better Dam Well Be or One of them is Dead Ass wrong... Mandrin's Model and nm Theories both Demonstrate release can Occur without the Hinge(Hand) Slowing Down.... So where the Hell is the Disagreement???? If they are Mathematically equivalent then it makes more sense to use Mandrin's Model.... Simply because nm has not as yet Developed a Model using his Basis.....

Cheers

 

[mandrin]

I'm Bettin nm's Theories and Mandrin's Model are in Mathematical Agreement.... They Better Dam Well Be or One of them is Dead Ass wrong... Mandrin's Model and nm Theories both Demonstrate release can Occur without the Hinge(Hand) Slowing Down.... So where the Hell is the Disagreement???? If they are Mathematically equivalent then it makes more sense to use Mandrin's Model.... Simply because nm has not as yet Developed a Model using his Basis.....

Cheers

Bronco Billy, I hope you have some empathy for me when I note that after all my efforts to explain one thing you conclude exactly the opposite.

 

[Bronco Billy]

YIKES

Bronco Billy, I hope you have some empathy for me when I note that after all my efforts to explain one thing you conclude exactly the opposite.

Hi Mandrin

YIKES ...............

Cheers

 

[mandrin]

Ok, so is acceleration or rate of acceleration causing the negative torque you spoke on above? If not, what causes that negative torque?

Bigwill,

It is evident from above that the torque is first negative and after a short while changes in sign.

For further explanations you better ask our resident science expert Jeffmann.

He will have a redundant answer typed out before you can even formulate your question.

Just be sure to ask for a child-like response. He will understand.

 

[Bigwill]

Bigwill,

It is evident from above that the torque is first negative and after a short while changes in sign.

I can't make heads or tails of the above. Besides, I never questioned whether or not there was a negative torque, so I didn't really need proof either way (thanks anyhow). I just wanted to know if accelaration caused the negative torque (if so, how), and if not, what is causing it (and how). I'm not picking a fight; not interested. It's a real, wysiwyg question.

 

[mandrin]

I can't make heads or tails of the above. Besides, I never questioned whether or not there was a negative torque, so I didn't really need proof either way (thanks anyhow). I just wanted to know if accelaration caused the negative torque (if so, how), and if not, what is causing it (and how). I'm not picking a fight; not interested. It's a real, wysiwyg question.

Just as inertia force a bit of recognition goes a long way.

 

[Bigwill]

So, what is the negative torque? And when it goes (or strives to go) positive, what forces override it and allow the club to line up with the arm at the proper time?

 

[Bronco Billy]

YIKES

YIKES.... That Ain't AlgerBra ...........