the COAM myth

Re: the COAM myth

Postby Range Rat » Thu Jan 14, 2010 8:53 am

Mandrin: A quick question the answer to which will answer in my mind the question of COAM.

Can an astronaut, in a weighless environment and floating, increase their rotational velocity by moving their arms inward much like a figure skater does. Assuming of course they are in a rotary motion with extended arms?
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Re: the COAM myth

Postby biomechanic » Thu Jan 14, 2010 9:09 am

Macs,
There is no force applied the human body ... The human body is a closed system and creates speed within the system...
Our bodies creates rotational speed not forces.... conservation of momentum drives and powers the golfswing... Kinetic link...
Coam can occur in the arm and club relation ship..... ass the arms decel the hands act as a pivot point and the club releases there is the angular speed of the club.... In golf you measure two speed linear speed and angular speed.... The angular speed the clubs snaps away from the wrist creating ball compression..
In TGM words 4 barrell swing with a snap release

Arm rotation..... the arms continually rotate in a golfswing and there is no external force applied to the arms... there axis point is the left shoulder joint centre...
The arms function are the left arm swings and rotates... the right arm drives.... left arm is club face control the right arm is power direction and ball compression (power delivery) ..... Optim is all the speed is head through x straight at the target
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Re: the COAM myth

Postby mandrin » Thu Jan 14, 2010 9:46 am

Range Rat wrote:Mandrin: A quick question the answer to which will answer in my mind the question of COAM.

Can an astronaut, in a weighless environment and floating, increase their rotational velocity by moving their arms inward much like a figure skater does. Assuming of course they are in a rotary motion with extended arms?

Range Rat,

Quick answer......yes. It is THE perfect situation for COAM. There are no net external torques acting on the astronaut. Regarding angular momentum the astronaut constitutes hence an ideal closed system in which COAM applies. It would be very funny and interesting to make him try to swing a club. Conservation of angular momentum concerns inertial mass and not gravitational mass and it applies everywhere. No exceptions have yet been found.
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Re: the COAM myth

Postby mandrin » Thu Jan 14, 2010 10:04 am

biomechanic wrote:Mandrin,
Thanks for the laugh..... It's so hilarious reading your posts..... Sadly your so far from the truth it's a joke...

biomechanicc,

At least I make you laugh, definitely good for your health. In contrast to some who are grinding their teeth and are mad. Whilst laughing, don't forget to respond to my explicit invitation. I will wait patiently.

Discussing science seems to be really exciting some posters, some mad, some laughing. However, it is only science, not religion and definitely not sex. Boy, are people ever excitable nowadays, what if I really started touching on sex or religion. It would likely create an interesting collective orgasmic event.
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Re: the COAM myth

Postby mandrin » Thu Jan 14, 2010 1:07 pm

Lefthook wrote:
mandrin wrote:
conserve - to keep (a quantity) constant through physical or chemical reactions or evolutionary changes.
increase - to make greater or larger.

If you take increase to mean the same as conserve I am afraid that I can't help you way one way or the other. However, just in case, a longer back swing producing more club head speed is simply due to forces/torques acting over a longer time.....Newtonian elementary mechanics. Forget about COAM, can't be invoked. If you do than you are like a golfer believing that a par three hole requires 4 strokes. ;)


In explaining how a longer back swing works, you are implying conservation of kinetic energy. Yet you are explicit denying the same. Now this is what I call scientific schizofrenia.

To conserve doesn't mean to keep a quantity constant. It only means to save a quantity. Coam and acceleration goes hand in hand in the golf stroke.

To give you an example of a rotary system without coam: Tightening a nut. The nut has angular momentum while it is rotating. The harder you torque the faster it will turn. To put it simple, the nut doesn't conserve kinetic energy. It stops rotating as soon as you let go of the torque. The major part of the energy you put in is transfered to heat instead. No angular momentum is conserved. As opposed to what happens in a golf stroke.

Lefthook,

Things get worse. Some are mad, some laugh and now I am judged to suffer from scientific schizophrenia. What will be coming my way next time?

It is too fastidious, like in biomechanic's posts, to show point for point all the errors made. In a sense it reminds me of TGM. Everything is sort of there but also not quite correct and even sometimes definitely wrong, in a somewhat complicated crooked way. However to clearly spell it all out and clean it all up will take even more time than it took to write the book originally.

I simply suggest that you Google a bit, if you don't have any physics or dynamics text book around. Without any exception you will always find reference being made to COAM as applicable to systems being subjected to no net external torque.

For your information I like to attract your undivided attention to the fact that the C in COAM stands for CONSERVATION. If you ask any engineer or scientist what this word means they will invariably say that it means angular momentum remaining CONSTANT.

If you want to invent a physics different from the accepted standard and invent your own version of the universally accepted fundamental law of conservation of angular momentum, good for you and the best of luck. But it means that any scientific career becomes forbidden territory for you.

However, luckily enough for you, it does not prevent you from potentially having a decent or even having an excellent golf game.
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Re: the COAM myth

Postby mandrin » Thu Jan 14, 2010 2:17 pm

biomechanic wrote:Macs,
There is no force applied the human body ... The human body is a closed system and creates speed within the system...
Our bodies creates rotational speed not forces.... conservation of momentum drives and powers the golfswing... Kinetic link...
Coam can occur in the arm and club relation ship..... ass the arms decel the hands act as a pivot point and the club releases there is the angular speed of the club.... In golf you measure two speed linear speed and angular speed.... The angular speed the clubs snaps away from the wrist creating ball compression..
In TGM words 4 barrell swing with a snap release

Arm rotation..... the arms continually rotate in a golfswing and there is no external force applied to the arms... there axis point is the left shoulder joint centre...
The arms function are the left arm swings and rotates... the right arm drives.... left arm is club face control the right arm is power direction and ball compression (power delivery) ..... Optim is all the speed is head through x straight at the target


In any science book, treating biomechanics, there is usually great emphasis placed on ground reaction forces and all the subtle problems and techniques required to gather and interpret the complex signals obtained from force platforms, measuring these forces. There is a very good reason for that since it is the ground reaction force usually being the ONLY SIGNIFICANT external force acting on our body, being it walking, running, golfing and a host of other activities.

Now our dear friend, biomechanic, our resident biomechanical expert, clearly states without any ambiguity whatsoever, in his post -

" There is no force applied to the human body ... The human body is a closed system and creates speed within the system... "

biomechanic, you are really doing no good to your profession of biomechanics, by making such fundamental errors. Who is going to believe you, from now on, if you are so completely and desperately wrong regarding the very foundation of biomechanics, both literally and metaphorically.

The golfer earth interaction force, which makes golf possible, this ground reaction force, the only external force acting on a golfer, you are unequivocally denying its existence, since you state that there is no force applied to the body, and concluding, as a consequence, that the body acts as a closed system.

I only took one specific example but could go on with many of biomechanics statements. Probably he is laughing so much that he has likely lost his wits. However I don't want to spend too much of my time furthering the scientific education of biomechanic, which needs indeed badly a bit of polishing.
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Re: the COAM myth

Postby macs » Thu Jan 14, 2010 2:21 pm

Lefthook
I am trying things to not escalate here. COAM is a composite of w m r ^2. Its not the same as velocity. And it is constant which means whatever tipped the object to move thats it no more force internal or external. Yes in such a system if you decrease the radius or the mass, velocity will increase but it does not apply to the golf swing becasue we are constantly applying more force/torque. The most prominent examples are planets orbiting and electrons.
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Re: the COAM myth

Postby Lefthook » Thu Jan 14, 2010 8:08 pm

mandrin wrote:
Lefthook wrote:
mandrin wrote:
It is too fastidious, like in biomechanic's posts, to show point for point all the errors made. In a sense it reminds me of TGM. Everything is sort of there but also not quite correct and even sometimes definitely wrong, in a somewhat complicated crooked way. However to clearly spell it all out and clean it all up will take even more time than it took to write the book originally.

I simply suggest that you Google a bit, if you don't have any physics or dynamics text book around. Without any exception you will always find reference being made to COAM as applicable to systems being subjected to no net external torque.

For your information I like to attract your undivided attention to the fact that the C in COAM stands for CONSERVATION. If you ask any engineer or scientist what this word means they will invariably say that it means angular momentum remaining CONSTANT.

If you want to invent a physics different from the accepted standard and invent your own version of the universally accepted fundamental law of conservation of angular momentum, good for you and the best of luck. But it means that any scientific career becomes forbidden territory for you.

However, luckily enough for you, it does not prevent you from potentially having a decent or even having an excellent golf game.


I am an engineer, and mechanical engineering is a significant part of my MSc degree. Coam wasn't on the agenda as far as I can remember, so I followed your tip and checked it out. The only surprise for a while there was the the rotating object club will speed up when the swing radius is decreased, and it will slow down when it's swing radius is increased.

Intuitively it is not difficult to realize how this can happen. For instance two planets moving in elliptical patterns, kept in orbit by each other's gravity. Because of gravity the speed will increase as they move towards each other and decrease as they move away from each other. It's an energy storage system that oscillates between kinetic energy and potential energy.

The coam seems magic in as far as with a narrow swing radius (snap release with small pulley) the swing speed will increase while coam is constant. But there is a big "BUT" in the coam magic. You don't have some magic gravity to help you reduce the pulley, so you still have to do good old Newtonian work to increase the swing speed. With a good stroke you may transfer a significant amount of energy from the pivot and arms to the club head. But you'll have to work for it. Coam doesn't do it for you. The speed sequences in bio's kinetic link charts tells half of the story. The other half is: THe club doesn't pick up speed because you slow down. You slow down because you deliver energy to the club. There's hard work involved.

Coam provides the explanation why rotating systems, isolated from the environment continue to rotate, and how it unfolds. And it also explains why isolated systems who do not rotate can't begin to rotate by themselves. The energy storage in a rotating system is basically the same animal as the energy storage in a linear moving system 1/2 mv^2. But quite similar to conservation and accumulation of kinetic energy, you can also conserve and accumulate coam at the same time. Your theoretical experiments shows that to a large extent.

As far as your model work goes, it still looks impressive, but your argumentation is flawed. Coam is THE explanation regarding the circular movements in isolated systems. But you have turned it around and said: Therefore it doesn't apply when the system isn't isolated. Which is flat out wrong. It's the same thing as saying that the water is cold because you're still warming it up. And: The warehouse is empty because your still bringing in goods. There's no accumulation without conservation.

It doesn't take an engineering degree to see that your model of the double pendulum with torque accumulates am. It's there in the charts. Am increases yet the torque is constant. Sometimes the simple explanation si the best. In this case: COAM. It is also easy to see the relationship between the isolated system and the torqued system - in how am is redistributed between the arm and the club. If you combined the two models - first torque and then freewheeling, you would have the perfect model of how am is accumulated and conserved. And also a good illustration of how a golfer can get totally disconnected but still partly get away with it.

If you have an issue dealing with external forces - feel free to include the whole world in your model. Let nothing but the golfer and the club move. The am in the golfer + club an the am in the rest of the world will of course zero each other out. But neither the golfer nor the club cares about how their ground forces affects the life on March.

I am not suggesting that coam is a superb concept that somehow unlocks a mystery of good ball striking. I don't understand the hype surrounding it. If there is one. Personally I think accumulation and redistribution of kinetic energy is far more relevant basis for understanding the stroke mechanics. But even though I am absolutelly certain that coam happens.
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Re: the COAM myth

Postby caedus » Thu Jan 14, 2010 8:28 pm

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
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Re: the COAM myth

Postby Lefthook » Thu Jan 14, 2010 8:31 pm

macs wrote:Lefthook
I am trying things to not escalate here. COAM is a composite of w m r ^2. Its not the same as velocity. And it is constant which means whatever tipped the object to move thats it no more force internal or external. Yes in such a system if you decrease the radius or the mass, velocity will increase but it does not apply to the golf swing becasue we are constantly applying more force/torque. The most prominent examples are planets orbiting and electrons.


He-he.

I'll take it easy.

Coam applies, but I don't see why we need it to understand the golf stroke. I think F*S (force * distance through the ball) + 1/2 mv^2 works better. So at least we agree on the consequences of coam.
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