the COAM myth

Re: the COAM myth

Postby Addington Arnie » Sat Dec 19, 2009 4:01 pm

PS...is there anywhere on this site teaching how to post pictures and video content?


There is a tech page on the student forum here:

http://lagpressure.com/forum/viewforum.php?f=71

Cheers, Arnie
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Re: the COAM myth

Postby mandrin » Sat Dec 19, 2009 4:07 pm

eagle wrote:
mandrin wrote:The post which led to being banned from iseekgolf – the COAM myth.

TGM people are all for science as long as it concurs with their views.

Conservation of angular momentum is not really part of their dogmatic views.

But perhaps they were afraid I would touch on their views about impact. ;)


That is interesting Mandrin, but help me understand, because I think I might not agree with you in regards to COAM. ( But I do agree with you regarding TGM people...they like science as long as it agrees with their views..... )And by the way, just because someone can impressively recite chapter and verse of the Yellow Book repeatedly with great speed and enthusiasm, it does not mean what they say is true...reality cannot be suspended. But it may help them dupe themselves and others.

And please remember, I am not an engineer, and have had only a year of college level physics, many years ago.... I consider myself a physics "hacker/duffer/20 handicapper". So forgive me if I present stupid questions. But I am curious. And I still think that right thinking may produce better results( still waiting!!) I liked what Gerry said recently on another post...something like "there's no competition here, we're all just seeking reality." That's where I'm coming from.

Reading your example, you say a golfer at the top of his backswing has no angular momentum. I agree. But, does he not have potential energy , which can be converted to kinetic energy, and thus angular momentum?

You give some good thought experiments....here's another I borrow from Bertholy: How can can a man, standing with his arms to the sky, lift a weight of 150 pounds? ....Answer: by sitting on a teeter totter and lifting the weight on the other side of the fulcrum( and thus allowing his potential energy to be converted kinetic energy).

So in your example, can't the golfer at the top of his swing, let his weight drop, and let his arms fall(free ride), and pivot against the ground , to create energy and momentum, some of which creates angular momentum( converts the momentum of the falling arms and club to angular momentum)? And must not this angular momentum be preserved?

This is similar to your example,how the diver and skater use their potential energy to create their angular momentum. They didn't just start rotating from scratch, they have to use their own potential energy and gravity to create and transform it. So, would the example of the diver and skater be more accurate if one expanded the time of the experiment to BEFORE they were spinning, rather than start the example at a point in time when they are already spinning? Either that, or should one consider the golfer starting at a point in his downswing when he is already turning towards the target, and thus have components of his turning assembly that have angular momentum?


Eagle,

Excellent questions. You are rather correct in your line of thinking but it is all a measure of the relative importance. Moreover you left out of the equation the most important factor – contracting muscles, creating torques.

First of all, even if feel wise it might be very present, and indeed quite often referred to as free fall into the slot, potential energy does not play a significant role in a full fetched golf swing. The late Prof Jorgensen was probably the first to point this out. Its contribution is only in the low percentage bracket. There is some limited form of elastic potential energy due to stretch-shortening cycle of muscles but here again it constitutes only a minor possible contribution.

There is however a factor which might feel like potential energy but is related to the brains being geared very strongly to avoid and release uncomfortable feelings. Winding up fully can be very painful at the very top and the instinctive reaction to quickly release this unpleasant sensation might feel as having created and subsequently releasing potential energy.

Therefore the bulk of any work done, creating kinetic energy and angular momentum, is primarily a matter of muscles contracting in a proper sequence at the various locations along the bony levers of our bodies, generating torques. The back swing should not be viewed as creating potential energy to be converted into kinetic energy / angular momentum in the down swing, as is very frequently done in articles or golf instruction books.

The back swing is simply required to create sufficient space so that the contracting muscles have enough time to accelerate the clubhead long enough to create adequate clubhead impact speed. The basic notion in TGM of power accumulators is therefore also incorrect. There is nothing significant accumulated in the back swing. Neither power nor potential energy.

Hence the basic mechanism is the following. A golfer wants a high clubhead speed at impact. Since he he uses his feet as anchors he can only rotate and add some minor lateral displacement of the upper body. By rotating the clubhead behind his back the golfer creates a substantial displacement for the clubhead, 15 to 20 ft, during which it can be accelerated during the down swing.

An muscular athletic golfer can get away with a rather short back swing. Tender juniors or female golfers have no choice but to use a long flowing down swing to create adequate clubhead speed. It is an equation of magnitude of torques developed versus the space/time during which they can be active.

The golfer creates some angular momentum in the back swing but since he reverses direction, hence going through zero speed, he does not preserve it for the down swing.

The figure skater does not use potential energy. He uses his muscles to generate angular momentum. At the onset of a spin he creates explosively a certain amount of angular momentum, torquing against the ice, and than conserves it for the duration of the spin.

The diver similarly also creates the angular momentum explosively during the departure with the board. During the dive there is a conversion of potential energy into kinetic energy but the initial amount of angular momentum remains constant during the whole of the dive.

I don't blame anyone with having problems with potential energy. It has been depicted so often universally in golf as being created in the back swing that one is inclined to believe it with out any second thought whatsoever about the issue. Golf is rather prone to gather up this kind of false semi-scientific notions. :)
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Re: the COAM myth

Postby lecoeurdevie » Sat Dec 19, 2009 4:32 pm

I'd pay good money to see some people hit it on a range and put their money where their mouth is.
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Re: the COAM myth

Postby mandrin » Sat Dec 19, 2009 6:13 pm

lecoeurdevie wrote:I'd pay good money to see some people hit it on a range and put their money where their mouth is.

If I got paid good money for every post like yours on various forums I would be rich. Very original indeed. :lol:
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Re: the COAM myth

Postby lecoeurdevie » Sat Dec 19, 2009 6:41 pm

What's your career tournament earning totals big boy? I got a little over six hundred thousand reasons to express my opinion..
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Re: the COAM myth

Postby lecoeurdevie » Sat Dec 19, 2009 6:50 pm

But then again what's money anyway, the only reason I turned pro was for the free shoes..
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Re: the COAM myth

Postby Pippolo » Sat Dec 19, 2009 7:02 pm

lecoeurdevie wrote:But then again what's money anyway, the only reason I turned pro was for the free shoes..



You get free shoes??? Jealous... :mrgreen:
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Re: the COAM myth

Postby mandrin » Sat Dec 19, 2009 7:27 pm

lecoeurdevie wrote:What's your career tournament earning totals big boy? I got a little over six hundred thousand reasons to express my opinion..

lecoeurdevie wrote:But then again what's money anyway, the only reason I turned pro was for the free shoes..

Funny, how some, as soon as they are able hitting a little golf ball, feel so superior. Big time macho macho.... :lol:

Glad you didn't care about the money, am sure you did give it all to the poor and just kept the shoes. :mrgreen:
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Re: the COAM myth

Postby lecoeurdevie » Sat Dec 19, 2009 7:35 pm

If we're being honest, a lot of that money went toward the experimantal therapies for my Mom's MS that Blue Cross/Blue Shield wouldn't cover and some more went toward my PhD after the light bulb cicked on that chasing a little ball across a field doesn't give a life meaning and purpose or help anyone. I still have the old Classics though.. Does that make me vain?

Keep going, gimme your best shot. Take your time; it's entertaining.
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Re: the COAM myth

Postby twomasters » Sat Dec 19, 2009 8:12 pm

Here's 2 classic multiflash photos of the golf swing-- is this in tune with your diagram Mandrin?

This is from a book I dug out that I have. It is called The Four Magic Moves To Winning Golf by Joe Dante published in 1963. It has an entire chapter on COAM and is an interesting read. i will try and type it all in when i get around to it- but wanted to post the pics for now. Thought it was way ahead of it's time for being an almost 50 year old book...
by the spacing of the hand and sleeves- you can see hand/arm slowdown approaching impact and then hand/arm speedup again--- obviously this is only one golfer but the chapter spells out more which i will add later

I'm not an expert by no means on it-- just thought it intriguing to rip this book from my shelf to look at and there it was with an entire chapter about COAM which i had never heard of before until the last day or so reading this part of the forum
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