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Post by imperfectgolfer on Jul 12, 2012 23:21:03 GMT -5
Virtuoso, nmg wrote-: "If you tie a rope to your car's bumper and lean into it but the car does not move... you have not done any work." That may be true according to nmg's high school physics definition where work requires movement of the car, but it is work according to my definition of work - which relates to human energy expenditure. Try pulling a car with the attached rope for a continuous time period of 1 hour and then tell me whether you perceive that have expended energy in your hopeless attempt to move the car. Try another experiment - grab a flag pole with your right hand and try to dislodge the pole by continuously contracting your right biceps muscle. If your biceps muscle is isometrically contracting, it is using a greater amount of energy and therefore working more actively than it was working at rest - even though there is no isotonic activity of the biceps muscle (that can only happen if you dislodge the pole and cause the pole to move towards you). Using that perspective, the hammer thrower is not only expending human energy to rotate his torso, and therefore the hammer-ball, prior to release of the hammer-ball - he is also expending energy when he maintains his spinal inclination bend posture during the process of continuously maintaining a constant radius of his hand arc path (resisting the CF-loading pull of the ball that would pull him forward over his toes if he wasn't isometrically contracting his back muscles in order to maintain his spinal posture). Consider again Miura's diagram. He is applying a normal force of 414Nm at impact - even though he is not doing any more "work" according to the high school physics definition of "work" (because the hand arc radius has not changed and it has remained constant throughout the entire downswing action). Jeff.
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Post by nmgolfer on Jul 13, 2012 7:27:07 GMT -5
like i said... perversion of THE language leads to misunderstanding and confusion.
nmg
PS I believe Jeff has posted copyrighted image
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Post by virtuoso on Jul 13, 2012 12:54:35 GMT -5
Ok thanks to both you guys, let me chew on this stuff and get back to you.
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Post by imperfectgolfer on Jul 13, 2012 13:33:48 GMT -5
Consider this statement-: "perversion of THE language leads to misunderstanding and confusion."
I don't think that the english language is being perverted when one states that an isometrically contracting muscle is working harder than the same muscle when it is not actively contracting. I think that misunderstanding and confusion is more likely to occur when one arbitrarily adopts a rigid, one-sided, rule on how to use certain english language words (like "work") in a public forum.
Jeff.
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Post by virtuoso on Jul 13, 2012 15:07:45 GMT -5
guys, quick question:
When the golfer performs the "Lean back" (whether it is "work" or not) to counterbalance the CF-loading, is it just muscular contraction with the same body aligments or can the body change alignments such that the orientation of their body around their body cg is in a more effective position to play the "tug-a-war" so to speak.
Also, when a golfer falls out over their toes (which is the direction they always fall) due to being unprepared to counterbalance cf-loading, ponder this thought experiment:
Since cf-loading can be measured as a "dynamic pulling weight", and the acceleration of gravity can be measured as a weight, are the unprepared, falling golfers experiencing a simulation of either (a) the direction of gravity being shifted suddenly, or (b) their own body cg being suddenly displaced out past their toes? In other words, there is a sudden net resultant force from the combination of gravity and cf that they weren't prepared to stabilize against.
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Post by imperfectgolfer on Jul 13, 2012 17:30:31 GMT -5
Virtuoso,
I think that what really causes a golfer to fall forward over the toes in the early/mid downswing is not the effect of CF-loading, which only becomes operational in phase 3 of the downswing (between P6.3-P7). It is the fact that we swing the arms/club downwards-and-forwards-and-outwards towards the ball. To counteract that "unbalancing influence" one must brace oneself by using one's back musculature (that isometrically maintain one's spinal bend inclination) and also via the biomechanical mechanism underlying David Lee's "counterfall motion", which is biomechanically related to an active "left hip clearing action" that dynamically directs one's lower-mid torso weight inside-left in a direction that is approximately 30-70 degrees left-of-the-target.
To counterbalance the effect of CF-loading (which happens between P6.3 and P7) is much easier and one simply has to maintain one's spinal bend inclination throughout the downswing and followthrough - and that obviously involves the isometric contraction of back musculature. The motion of the left shoulder up-and-back ("throwing a drunk off one's back" motion) that happens between P6.5 and P7 also counteracts the effect of CF-loading. One doesn't have to "pull upwards with all one's might" as BM recommends for phase 3 of the downswing - as that exaggerated pulling-up motion can shorten the hand arc radius excessively and lead to inconsistencies in the clubhead arc path through the immediate impact zone.
Jeff.
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Post by virtuoso on Jul 13, 2012 18:38:57 GMT -5
I read a lot of David Lee's stuff a few years ago, and visited with him briefly as well. I thought he had some cool insights about the golf swing. But i also saw him say something on a vid about ball-club collision physics--thought he was pretty weak in that area.
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Post by nmgolfer on Jul 13, 2012 18:56:10 GMT -5
Virtuoso, I really liked some of what David Lee had to say. But then some of what he said made me want to vomit too. He's a mixed bag The forum is called 'Newton' golf for a reason. I think we should use the language of physics the way Newton intended. He would be rolling in his grave if he knew how some of his finely honed language is being perverted these days. I need more time to think about what you wrote in regards to dynamic balance and will respond to that later later! nmg I read a lot of David Lee's stuff a few years ago, and visited with him briefly as well. I thought he had some cool insights about the golf swing. But i also saw him say something on a vid about ball-club collision physics--thought he was pretty weak in that area.
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Post by imperfectgolfer on Jul 13, 2012 20:30:35 GMT -5
Consider this statement-: "I think we should use the language of physics the way Newton intended. He would be rolling in his grave if he knew how some of his finely honed language is being perverted these days."
We are discussing golf swing mechanics/biomechanics in this golf forum and not Newtonian physics. Therefore, we do not have to rigidly use common english language words like "work" in a strictly Newtonian sense - even if nmg harbors an overly strong pro-Newtonian bias in his usage/interpretation of common english words. nmg's rigid/narrow personal biases obviously do not represent the "gold standard" in this forum when it comes to the issue of how best to use common english words like "work". If he wants to impose a rigid Newtonian bias on the expression/interpretation of common english words frequently used in discussions re: golf swing mechanics/biomechanics, then he is free to start his own golf forum where he can arbitrarily establish his own language-use rules.
Jeff.
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Post by nmgolfer on Jul 13, 2012 20:46:07 GMT -5
Consider this statement-:"We are discussing golf swing mechanics/biomechanics in this golf forum and not Newtonian physics. Therefore, we do not have to rigidly use common english language words like "work" in a strictly Newtonian sense - even if nmg harbors an overly strong pro-Newtonian bias in his usage/interpretation of common english words. nmg's rigid/narrow personal biases obviously do not represent the "gold standard" in this forum when it comes to the issue of how best to use common english words like "work". If he wants to impose a rigid Newtonian bias on the expression/interpretation of common english words frequently used in discussions re: golf swing mechanics/biomechanics, then he is free to start his own golf forum where he can arbitrarily establish his own language-use rules."
Jeff is free to pervert the english language as he see fit. We are free to reject his inaccurate misuse of physics terminology when discuss golf swing mechanics/biomechanics. My entire effort in participating in golf forums has been directed at debunking myths which most often are caused by a misuse of the english language. That will not change.
I have an email into Rand owner of this forum trying to determine exactly who's it is. Is it Jeff's or is it Rands? Rand started it when Jeff made himself unwelcome everywhere else but does that make it his? I'd like clarification because it seems Jeff is morphing into a petty tyranant of sort who has decided he gets to decide what is and is not acceptable on Rand's forum. Rand? Where are you buddy?
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Post by nmgolfer on Jul 13, 2012 20:52:37 GMT -5
Virtuoso,
The direction of gravity never shifts. It always pulls towards the center of the earth. The answer is b. CG displaces due to interial forces acting on the golfer. Better golfers are prepared for it and counterbalance accordingly. Better golfers take advantage of these inertial through dynamic balance in the manner David Lee describes.
PS anyone who thinks activating any one or any set of muscles in the human body can counteract these inertial forces is in my humble opinion crazy. That won't work as duffer's soon learn or quit in disgust if they don't. Said golfer must "counterbalance" using the connection to earth at the feet real positive no net work producing inertial forces.
PSS Virtuoso... it seem BM is now on the right track in regards to the physics of the golf swing. If you don't mind my asking what is your moniker on that forum?
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Post by virtuoso on Jul 13, 2012 22:07:23 GMT -5
Hey nmgolfer, im virtuoso there also.
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Post by imperfectgolfer on Jul 14, 2012 8:52:09 GMT -5
nmg wrote-: "anyone who thinks activating any one or any set of muscles in the human body can counteract these inertial forces is in my humble opinion crazy. That won't work as duffer's soon learn or quit in disgust if they don't. Said golfer must "counterbalance" using the connection to earth at the feet real positive no net work producing inertial forces."
I never stated that one should not be connected to the earth when using isometric contraction of body musculature to counteract the inertial forces. A hammer thrower is obviously exerting considerable force into the ground when he "leans back" in order to maintain his spinal bend inclination during the pre-release phase of his hammer-throw action. A hammer-thrower couldn't perform well on an ultra-slippery ice rink, and neither could a golfer.
Jeff.
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Post by tomdavis76 on Jul 14, 2012 18:38:32 GMT -5
Consider Jeffy's irrational comment. See - jeffygolf.com/showthread.php?393-Is-anyone-in-golf-stupider-than-Michael-FinneyHe states that Federer was hitting a top-spin shot and that a top-spin shot must involve the ball being struck well below the center of the racquet face. What!!! When a good tennis player hits a top-spin shot, he still attempts to hit the ball in the center of the racquet face. However. the racquet face path is upwards - moving from "below-to-above" a horizontal plane through the immediate impact zone. There is zero evidence in that video that Federer's hand motion, and therefore racquet face path, is other than horizontal. That video simply shows an off-center racquet face strike. Top-spin is produced when the racquet face path is different to the racquet face orientation (which should face the target), and it does not imply an off-center strike. The same principle applies to a tennis player producing slice spin - the ball should be struck in the center of the racquet face (which should face the target), but the direction of the racquet face path should be from "above-to-below" relative to the target (the exact opposite scenario compared to top-spin). Jeff. Jeff- Don't misquote me. I never said a player "must" hit it low on the racquet for a topspin shot. But often they do, just as they often hit it high on the racquet for slice spin. Anyway, I agree with your IP: I still have no idea what point Finney is trying to make, and that thread is in its 7th page! Jeff
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Post by tomdavis76 on Jul 14, 2012 21:19:25 GMT -5
BM made the following comment in that thread. "Pure and Simple. You CAN NOT make the face do ANYTHING during impact—even on purpose. It is really a shame that folks waste time with this stuff. Goofy. " That's not the critical issue. I think that the important issue is whether having a stable left wrist through the immediate impact zone (between P6.9 -P7.2) decreases the amount of clubface rotation due to an off-center strike. Jeff. Do you believe a stable left wrist (whatever that is) can somehow minimize whatever effect to the face angle is caused by a strike where the ball is not in alignment with the CG? What evidence do you have that proves that may be true? I think what BM is saying is NO it doesn't matter if the left wrist is bowed or cupped or flat, the effects of an off center strike will not be affected by any kind of hand/wrist manipulation. Actually, common sense tells you that a player that is actively rolling the right hand over the left through impact will have a clubface that rapidly shuts on a heel hit and maybe doesn't deflect open at all on a toe hit. Video evidence of both has been recorded by Kelvin Miyahira and is on Youtube and posted on my site. For players that "supinate early" and release "closed to open", as some might say, common sense would also suggest that heel strikes would result in less closing (relative to a roller) and center strikes might actually deflect the face open. Again, this is exactly what has been captured on video, uploaded to Youtube and posted on my site. For some reason, Brian and company don't want to believe that distinctly different release styles, that impart very different forces to the shaft, can result in different clubface behavior through impact. That makes no sense at all and is inconsistent with what can clearly be seen on high-speed video. Jeff
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