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Post by imperfectgolfer on Sept 26, 2011 14:00:00 GMT -5
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Post by imperfectgolfer on Sept 26, 2011 18:49:57 GMT -5
I see that Greg asked this question about what's a "normal force" at the BM forum.
MJ replied as follows-: "Tangential would be like throwing a spear off the circle, normal would be the force that keeps the spear on the circle and faces towards the golfer at the bottom. The normal force at the bottom is far greater than any tangential force during the swing."
I think that he is stating that the normal force is a CP force that is directed centrally towards the center of the had arc path circle. At low point, the club has caught up with the left arm and there is therefore no tangential force (CF-releasing force) present. Prior to low point (between the time the club starts to release and low point) the club is being subjected to two forces - i) a CP-force due to the fact that the hand arc path is circular and a ii) a CF-releasing force (tangential force) that is due to the club's gained angular momentum and the club gains angular momentum during the release phase of the swing according to the physics of the D'Alembert principle (when the hand arc path changes direction continuously - due to the fact that the hand arc path is circular).
If I am correct in my understanding of the term "normal force", then I cannot understand what's the utility of using that term from a golf swing mechanics/biomechanics perspective. Can you?
Jeff.
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Post by imperfectgolfer on Oct 11, 2011 10:03:31 GMT -5
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Post by imperfectgolfer on Oct 13, 2011 21:15:02 GMT -5
Micahel Finney made the following statement in the 3jack forum.
"Yes, the correct use would be normal to the club head velocity vector.....not the swing arc......he shouldn't use normal force.....you guys are right......I have been voting for radial force, but homer mucked that all up.....of course he could use centripetal but the moraders and the s&t'ers mucked up that one....we aim to please."
He writes about a radial force that is normal to the clubhead velocity vector. What is producing that radial force from a biomechanical perspective (considering that the straight left arm is merely an inert lever)?
Jeff.
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Post by imperfectgolfer on Nov 6, 2011 17:19:49 GMT -5
As best I can understand what creates BM's "normal force" at impact it is due to an elevation of the left shoulder socket in the later downswing. In other words, it is due to a biomechanical action of the golfer and it acts through the effect of that biomechanical action on the grip end of the club producing parametric acceleration of the club. Here is how a BM-groupie explains what causes a normal force. See - www.brianmanzella.com/golfing-discussions/16291-going-normal.htmlHe writes-: "when the clubhead catches up with and straightens out the shaft rather than lagging behind the shaft putting a force across it." I guess that the clubshaft wasn't straight before the clubhead produced a "force" to straighten it!!!! He even believes that "force-across-the-shaft" is due to the clubhead lagging behind the shaft. That gross lack of understanding is partly a reflection of how well BM explains concepts in his forum, and partly due to the limited intellectual capacity of some BM-groupies. Jeff.
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Post by gmbtempe on Nov 7, 2011 10:34:18 GMT -5
As best I can understand what creates BM's "normal force" at impact it is due to an elevation of the left shoulder socket in the later downswing. In other words, it is due to a biomechanical action of the golfer and it acts through the effect of that biomechanical action on the grip end of the club producing parametric acceleration of the club. Here is how a BM-groupie explains what causes a normal force. See - www.brianmanzella.com/golfing-discussions/16291-going-normal.htmlHe writes-: "when the clubhead catches up with and straightens out the shaft rather than lagging behind the shaft putting a force across it." I guess that the clubshaft wasn't straight before the clubhead produced a "force" to straighten it!!!! He even believes that "force-across-the-shaft" is due to the clubhead lagging behind the shaft. That gross lack of understanding is partly a reflection of how well BM explains concepts in his forum, and partly due to the limited intellectual capacity of some BM-groupies. Jeff. $$$$
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Post by gmbtempe on Nov 8, 2011 12:23:08 GMT -5
There is something inherently illogical in what is being advocated this time by the BM and his groupies. A pure axial load serves absolutely no purpose. BerntR tried to explain it to them but the majority and the guru are incapable of grasping what he said. Only the off axis component of the hand force serves to increase club-head speed. Best way to think about this parametric acceleration they've recently glommed onto is to think of a hammer thrower. He spins round multiple time to generate hammer speed before he releases. He's spinning because that is required to generate the off axis component to the force he's imparting. While a hammer thrower may be able to spin 720 or 1080 degrees before he releases, the golfer only has about 100 degrees max... (the last two stages of the stroke). Thanks, makes a lot of sense. I have no idea why they are trying to obfuscate Brents opinion as he makes lots of great points.
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Post by imperfectgolfer on Nov 8, 2011 12:51:28 GMT -5
I think that it's the off-axis rotation of the hands that generates swing power. I think that the golf swing is primarily a rotary motion of the body/arms/hands.
Jeff.
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Post by imperfectgolfer on Dec 1, 2011 19:42:11 GMT -5
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Post by imperfectgolfer on Dec 2, 2011 13:06:54 GMT -5
nmgolfer, I disagree with your explanation. I think that a swinger moves a golf club by pulling on the grip end of the club, and that's the only "force" experienced by the club. Ben Hogan used the two-handed basketball analogy of throwing the basketball towards the target on the left side. The basketball is equivalent to the grip, and it only responds to a pull force exerted by the left hand and/or a push-force exerted by the right hand. In a swinger, I believe that all the force moving the grip towards the target should be exerted by the left hand. Here are capture images from my U-tube video - starting at the 5 minute time point. Image 1 shows me slipping my left hand under a grip that I have attached to the basketball. That will allow me to pull the basketball (equivalent to the grip). Image 2 shows me at the P5.5 position. Image 3 shows me just passed impact. Power was exerted on the grip between P5.5 and P7 via the sequential release of PA4 => PA#3. The red arrow shows the path of the left hand, and therefore grip. At impact, the left hand is still moving towards the target. Image 4 shows me at the P8 position. The blue arrow shows the path of the left hand between P7 and P8, and the left hand is continuously moving without stalling through the impact zone. Therefore, the "force" exerted on the grip is a pulling force in the general direction of the target through the impact zone. In this demo, I have ignored the fact that the hand arc path moves slightly upwards between P6.5 and P7 - due to the fact that the left shoulder socket is moving up-and-away, and that motion can add a small force that produces parametric acceleration. However, the main force exerted on the grip is the fact that the FLW leads the grip end of the club (pulling on the grip) throughout its non-stop motion along the course of the hand arc path between P5.5 and P8. The hand arc path is a circular motion, and only part of its motion can be perceived to be due to a centripetal force. Jeff.
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Post by imperfectgolfer on Dec 2, 2011 16:30:33 GMT -5
nmg,
I agree that in an active pivot action swing (like Mike Austin's) that the pivot action powers the left arm via the pivot-induced release of PA#4. Then the moving straight left arm pulls the grip along via its attachment to the grip - the left hand. From the grip end of the club's perspective, it only experiences the left hand pulling it along from P4 to P8, and it doesn't know that the left hand gets its pulling power from the active pivot-induced release of PA#4.
In the MA video, I believe that it is the rope that pulls the grip end of the club along, and the rope is simply a "piece of string" (equivalent to an inert straight left arm lever) that transfers the energy from the pivoting torso to the grip. The fact that the rope remains taut proves that the grip is being pulled, and not pushed. MA also straightens his right arm in an underhand throw action, but that doesn't make the grip end of the club moves faster than it is being pulled by the rope - because if it did then the rope would not remain taut during the downswing.
Jeff.
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Post by imperfectgolfer on Dec 2, 2011 21:11:10 GMT -5
nmg,
If you believe that the rope is not doing anything, that means that you don't believe in the pivot-induced release of PA#4 - then please explain to me how pivot-power is involved in his right hand toss swing action?
Jeff.
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Post by natep on Dec 2, 2011 22:37:48 GMT -5
Austin thought that the pivot's job was just to put you in position to hit (with a freewheeling clubhead via the hands). Throw from the top so that the clubhead is freewheeling during the bottom 3/4 of the downswing. Not pulling or dragging with the left arm.
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Post by imperfectgolfer on Dec 3, 2011 0:31:01 GMT -5
Natep,
If you believe that it is humanly possible to hit a 515 yard drive with a right arm swing action where the pivot action only gets one in position to perform a right arm swing action, then I am not surprised that you are capable of harboring that opinion!
Hopefully, other forum members are wiser. I received 12 out-of-circulation MA DVDs from a fan of my review paper on Mike Austin's swing, and it is clear to me after viewing many of them that MA was a TGM swinger who simultaneously performed a right arm throw action that was time-coordinated with his pivot-induced release of PA#4.
Jeff.
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Post by natep on Dec 3, 2011 0:38:18 GMT -5
Think whatever you want, I'm just telling you what the man said himself countless times. And I've used it to great success and still use that swing for my driver. I probably hit 50 drives this year over 360 in normal conditions during rounds of golf so I know for sure its not BS.
Why do you think he went out of his way to demonstrate that swing with the rope for the left arm? Have you watched Austinology? He says numerous times that you should NEVER pull with the left arm. You're just trying to fit everything into a little TGM box that simply isnt thorough or complex enough to include all swing theories and models.
By the way, what are the names of the 12 DVD's?
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