the COAM myth

Re: the COAM myth

Postby Lefthook » Thu Jan 14, 2010 8:34 pm

caedus wrote:Nice comeback Lefthook!! Mandrin I am wondering if your old enemy NMGolfer is already here or on his way. This could end up like Ali vs Frazier, no Mods to inhibit the musings


Good one :mrgreen:
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Re: the COAM myth

Postby macs » Thu Jan 14, 2010 9:06 pm

It's like in shot put is the acutaly shot point begins to accelerate and leave your hand when you reach peak accleration and deceleration occurs... as soon as deceleration of the amrs occurs conservation of momentum is paas through the to shot putt and leaves your hand accelerating....


Bio
Forgive my ignorance but did you train as a biomechanist at a University or only apprenticed while measuring movement patterns with a machine. I dont know if just the haste of your writing but you are not doing yuorself any favours by your writing. May be you should re-read your post before pulling the trigger. Conservation of momentum is a concept so we should say Angular (or Linear) momentum is passed to so and so. It does not make any sense to say conservation of momentum is paas through.
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Re: the COAM myth

Postby biomechanic » Fri Jan 15, 2010 9:02 am

Macs,
Was typing errors... Was flying out the door and didn't check before submitting post... You are right I should have checked before submitting my post....
Understudying under a biomedical engineer/ biomechanist.... On the job training doing biomechanics and training human motion in a long list of. Also studying a few years now... Previously played high level golf until I had an accident and ended my playing career... Became a golf coach, taught TGM up until 2007, when I started in the field I'm in now...

My mathematics etc is good although in result of my accident have a few issues with my writing... Due to my accident, I had to learn to walk again, also read, write and speak again... I was one lucky guy to survive my accident, I knocked on heaven's door a few times in both surgery....

Verbally know my stuff and can verbally communicate very well, although in writing to word and express something, I will be honest I can struggle at times... Although I am getting better and attending classes in this area...

Also due to my accident I had to learn to play golf again... Huge shock to the system for me was the last round I played before my accident shot 67... First game back I shot 108. This was very hard to chew on. Although gave me the drive to learn the game again, took around 12 months of hard work to shoot par... These days can shoot par comfortably on good days can shoot sub par...

Everyday you have to strive to improve and better yourself and for me has been a very long road to resume a normal life.
Bear with me regards my writing skills they will get better over time. Although trying to put what we do in layman's in writing, isn't easy at the best of times for anyone...
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Re: the COAM myth

Postby biomechanic » Fri Jan 15, 2010 9:45 am

P.S Mac's I work hands on testing athletes and training athletes biomechanical function, we work with athletes at all levels, although mainly working with world class athletes in the top of their field, like golf, cycling, running, tennis, baseball and a list of many other sports.
Senior Engineers have spent 20 years researching sports, They continually developing new techniques for training biomechanical functions for individual athlete's... We are already understand how the human body functions... We are at a point where our main research is training biomechanical function... by testing more and more training techniques, exercises and training programs for athletes...
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Re: the COAM myth

Postby macs » Fri Jan 15, 2010 12:10 pm

Bio
Apologies; forgive my ignorance again.
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Re: the COAM myth

Postby mandrin » Fri Jan 15, 2010 1:49 pm

A subject is better understood by looking at it from very different angles. So let's try another approach to explain COAM. Mathematics is not very appealing since it requires a special back ground. Discussing with various arguments is somewhat better but again it rapidly gets boring for most. A picture is worth a thousand words so let's take this angle of approach.

In Fig1 I have distilled the essence of the angular momentum behavior versus time of the various sport acts, which do obey COAM, and have done the same in Fig2 for a golf swing which does not obey COAM.

coam_22.gif
coam_22.gif (8.69 KiB) Viewed 4321 times

For the various sport acts, such as the figure skater's spin/twist, the board diver's jump, a trampoline pirouette, etc., there is a time interval where angular momentum is created followed by an interval, between t1 and t2, where it remains constant. This allows one to use COAM and the simple elegant generic relation :

w x r^2 = constant

However Fig2, representing a golf swing, shows a radically different behavior. There is some angular momentum generated in the back swing but is lost arriving at the top when starting the down swing. The downswing starts hence with zero angular momentum and generates a steadily increasing angular momentum till about impact. From there on it gradually reduces during the follow through. It is therefore not possible to use the very simple generic equation above for the golf swing.

coam_31.gif
coam_31.gif (6.84 KiB) Viewed 4321 times

We are dealing here with the very bare-bones basics so that there is a simple unambiguous situation. A real golfer is made up of various linked bodies, making a more detailed analysis rather complex. Also there is the matter of ground force. For those who might be interested, I have done an analysis of several linked bodies, including ground reaction force, again trying to restrict to bare-bones basics.

Analysis of conservation of angular momentum using model including ground reaction force

.
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Re: the COAM myth

Postby Lefthook » Fri Jan 15, 2010 4:34 pm

Nice work, Mandrin!
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Re: the COAM myth

Postby mandrin » Sat Jan 16, 2010 12:47 pm

Lefthook wrote:Nice work, Mandrin!

Complexifying things in science is easy as pie.
Simplifying is a more interesting challenge.
Thanks for the appreciation.
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Re: the COAM myth

Postby NRG » Sun Jan 17, 2010 3:45 am

Complexifying things in science is easy as pie.
Simplifying is a more interesting challenge.


:lol: :lol: :lol:

Mandrin, you're funny as well as clever.
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Re: the COAM myth

Postby Range Rat » Mon Jan 25, 2010 2:41 pm

Mandrin: Are you still out there somewhere? If you are, I have a math/golf question for you regarding parabolas. Don't know if that's your cup of tea but it will center on ball heights in flight at given distances. I'm looking for a formula that may not exist. We may have to do this on another area of ABS, but I thought this COAM area would be a good place to start.
You're ahead of where you were, and behind where you're going.
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