Yoda - you wrote-: "At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This Lag Pressure Point Pressure (1-L #7) is what is driving the Club, not the Clubshaft."
Could you please expand on your argument?
I believe that CF is primarily driving the clubhead and the peripheral end of the club (where the COG is located) and not the entire club (which consists of a clubhead, peripheral shaft, central shaft and grip end of the shaft). I believe that the hands are simultaneously driving the grip end of the club while CF is driving the clubhead and peripheral end of the club.
Your argument seemingly presumes that when the club starts to release and CF comes into play, that the hands are no longer driving the club. However, the hands are still moving the grip end of the club during the process of club release and they are applying a pull force on the club (in a swinger) while the club is in the process of releasing - and this pull force (which is at an angle to the COG of the club) adds supplementary angular velocity to the clubhead and peripheral end of the club during the release process.
HK's endless belt keeps moving while the belt moves around the end pulley, and the club is still attached to the endless belt and therefore subject to its continuous motional forces.
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Add additional point - I was writing my post and I didn't see that Yoda was simultaneously modifying his post to read as follows-: "the lag pressure point is what is driving the club" (see next post #204). I originally thought that Yoda was stating that CF was driving the club.
I then have to slightly modulate my argument. I cannot understand what it means when one states that PP#3 is driving the club in a swinger's action. I thought that PP#3 only senses/monitors clubhead lag pressure and that it doesn't drive the club. The club is driven in a drag loading manner by the left hand pulling on the club in a swinger's action. The right hand doesn't apply push-pressure drive via PP#3 in a swinger's action.
By the way, we are presumably talking about a swinger's action because there is no centrifugal pull in play in a hitter's action.
Yoda will independently decide whether he wants to expand on his post - per my request.
Jeff.
Last edited by Jeff : 12-21-2008 at 11:52 PM.
Reason: add additional comment in response to Yoda's modified post.
Yoda - you wrote-: "At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This is what is driving the Club, not the Clubshaft."
Could you please expand on your argument?
I already did. Immediately after posting, I added the following text (in red) to my post:
"At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This Lag Pressure Point Pressure (1-L #7) is what is driving the Club, not the Clubshaft."
You could not have known this as you were responding, and I have so notified you by Private Message. Therefore, as I've advised, please take the added text into consideration and amend/edit your post as you see fit. Thank you.
I was writing my post and I didn't see that Yoda was simultaneously modifying his post to read as follows-: "the lag pressure point is what is driving the club" (see next post #204). I originally thought that Yoda was stating that CF was driving the club.
And, Jeff, you were right!
Assuming the conventional Swinging motion -- which is what all these heretofore presented 'axis-string-ball' models have been about -- Centrifugal Force IS driving the Club. But, Jeff . . .
You've made a serious error.
Please re-read my post. You missed a word in your typed quote above, a very important word that I now will resurrect, return to its proper place, enlarge and highlight in red:
"This lag pressure point Pressure (1-L #7) is driving the club."
And the Lag Pressure Point Pressure is Centrifugal Force being transmitted through Pressure Point #3.
In both versions -- original or edited with additional information -- my post stands.
Yoda - you wrote-: "This lag pressure point Pressure (1-L #7) is driving the club."
The Lag Pressure Point Pressure is the result of Centrifugal Force transmitted through Pressure Point #3."
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I certainly don't understand your viewpoint.
I believe that CF only comes into play in earnest when PA#2 passively releases (left wrist uncocks passively), and the club releases.
In a swinger the club is loaded against PP#3 at the end-backswing - when the clubshaft is parallel to the ball-target line. At that time point, the only pressure felt at PP#3 is due the weight of the club. Then, during the early downswing, the left hand is pulling the club down to the ball (while the left arm is kept loaded against PP#4 via the pivot-drive). Under those conditions, the sense of lag pressure felt at PP#3 increases because the clubhead has inertia and resists following the hands - it "feels" like one is leaving the club at the top while the entire power package is being pulled down intact to waist level via the lower body shift movement. I don't believe that there is any CF in play during the early downswing because the hands are moving along the straight line portion of the U-shaped hand arc. If the hands are moving more-or-less in a straight line, then there is no centripetal acceleration of the hands, and therefore no need for a counterforce (a CF). During this phase of the swing, I cannot understand how CF can be driving the club via lag pressure at PP#3.
Then, when the hands move around the rounded curve of the U-shaped hand arc, the hands are moving in a circular arc that has a small radius. If the hands are tracking along a hand arc of small radius then the hands are traveling at an acute angle relative to the COG of the clubshaft and that induces the clubshaft to release with great speed (and this represents the CF release phenomenon). The clubshaft releases because it develops angular velocity, and the angular velocity is acquired because the direction of the pulling force at the grip end of the club is at angle to the COG of the club.
nmgolfer explains the release phenomenon in his html document.
From the delivery position (3rd parallel) to impact, the club releases by 90 degrees (left wrist uncocks 90 degrees). During that time period, lag pressure sensed at PP#3 should theoretically decrease for a given degree of hand speed - because the left wrist is uncocking. However, an experienced golfer maintains a sense of near-constant lag pressure at PP#3 by ensuring that the right elbow straightens with sufficient isotonic force that allows the straightening right arm to keep up with the left arm (and allows the right hand to keep up with the left hand). In other words, the degree of lag pressure sensed at PP#3 is the result of the interplay of a number of biomechanical phenomena that are occurring simultaneously - i) the left hand is being driven around the small pulley of the endless belt due to the release of PA#4 which drives the left arm towards impact; ii) the speed of left wrist uncocking (which occurs passively secondary to the speed of CF release of the club); and iii) the speed of right elbow straightening which allows the right hand to keep up with the left hand. In this scenario, - PP#3 senses lag pressure, but does not drive the club. I think that two forces are driving the club at this stage of the downswing - i) the left arm pulling the left hand towards impact due to release of PA#4 => left hand pulls the grip end of the club continuously along the endless belt track; ii) CF that causes the passive release of PA#2. However, because the release of PA#2 is passive and activated by the left hand pull action at the grip end of the club (with no push-force from the right hand), then it can be said that the source of all power driving the club is essentially derived from a left hand pull action where the left hand travels along a circular arc (around the end pulley of the endless belt system). It is the left hand that drives (pulls) the club during the downswing in a swinger's action and the CF release phenomenon is simply activated by the left hand pull action (according to the principles of the double pendulum swing model). I have no idea what you mean when you state that lag pressure sensed at PP#3 drives the club, and that the lag pressure is derived from the CF acting through PP#3.
Yoda - you wrote-: "This lag pressure point Pressure (1-L #7) is driving the club."
The Lag Pressure Point Pressure is the result of Centrifugal Force transmitted through Pressure Point #3."
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I certainly don't understand your viewpoint.
I believe that CF only comes into play in earnest when PA#2 passively releases (left wrist uncocks passively), and the club releases.
In a swinger the club is loaded against PP#3 at the end-backswing - when the clubshaft is parallel to the ball-target line. At that time point, the only pressure felt at PP#3 is due the weight of the club. Then, during the early downswing, the left hand is pulling the club down to the ball (while the left arm is kept loaded against PP#4 via the pivot-drive). Under those conditions, the sense of lag pressure felt at PP#3 increases because the clubhead has inertia and resists following the hands - it "feels" like one is leaving the club at the top while the entire power package is being pulled down intact to waist level via the lower body shift movement. I don't believe that there is any CF in play during the early downswing because the hands are moving along the straight line portion of the U-shaped hand arc. If the hands are moving more-or-less in a straight line, then there is no centripetal acceleration of the hands, and therefore no need for a counterforce (a CF). During this phase of the swing, I cannot understand how CF can be driving the club via lag pressure at PP#3.
Then, when the hands move around the rounded curve of the U-shaped hand arc, the hands are moving in a circular arc that has a small radius. If the hands are tracking along a hand arc of small radius then the hands are traveling at an acute angle relative to the COG of the clubshaft and that induces the clubshaft to release with great speed (and this represents the CF release phenomenon). The clubshaft releases because it develops angular velocity, and the angular velocity is acquired because the direction of the pulling force at the grip end of the club is at angle to the COG of the club.
nmgolfer explains the release phenomenon in his html document.
From the delivery position (3rd parallel) to impact, the club releases by 90 degrees (left wrist uncocks 90 degrees). During that time period, lag pressure sensed at PP#3 should theoretically decrease for a given degree of hand speed - because the left wrist is uncocking. However, an experienced golfer maintains a sense of near-constant lag pressure at PP#3 by ensuring that the right elbow straightens with sufficient isotonic force that allows the straightening right arm to keep up with the left arm (and allows the right hand to keep up with the left hand). In other words, the degree of lag pressure sensed at PP#3 is the result of the interplay of a number of biomechanical phenomena that are occurring simultaneously - i) the left hand is being driven around the small pulley of the endless belt due to the release of PA#4 which drives the left arm towards impact; ii) the speed of left wrist uncocking (which occurs passively secondary to the speed of CF release of the club); and iii) the speed of right elbow straightening which allows the right hand to keep up with the left hand. In this scenario, - PP#3 senses lag pressure, but does not drive the club.
Yes, Jeff, this is correct. Pressure Point #3 does not drive the Club. Centrifugal Force drives the Club.
Originally Posted by jeff
I think that two forces are driving the club at this stage of the downswing - i) the left arm pulling the left hand towards impact due to release of PA#4 => left hand pulls the grip end of the club continuously along the endless belt track; ii) CF that causes the passive release of PA#2. However, because the release of PA#2 is passive and activated by the left hand pull action at the grip end of the club (with no push-force from the right hand), then it can be said that the source of all power driving the club is essentially derived from a left hand pull action where the left hand travels along a circular arc (around the end pulley of the endless belt system). It is the left hand that drives (pulls) the club during the downswing in a swinger's action and the CF release phenomenon is simply activated by the left hand pull action (according to the principles of the double pendulum swing model). I have no idea what you mean when you state that lag pressure sensed at PP#3 drives the club, and that the lag pressure is derived from the CF acting through PP#3.
You have answered your own question: Centrifugal Force drives the Club.
To your previous post; I assume the addition was addressing this issue, that you highlighted in your response to Jeff:
Originally Posted by Yoda
"This lag pressure point Pressure (1-L #7) is driving the club."
And the Lag Pressure Point Pressure is Centrifugal Force being transmitted through Pressure Point #3.
In both versions -- original or edited with additional information -- my post stands.
I agree that the lag pressure point is driving the club. And by "driving" i mean adding energy to the club; In Newtons language - increasing 1/2 mv2.
BUT - I do not follow you when you say that the lag pressure is centrifugal force. (Actually I think centripetal force is the right term here, but it is beside the point I want to get through). The point is that centripetal force doesn't add energy to the golf swing. It only stores the energy that has been added throught the work of tangential forces:
A centripetal acceleration …
occurs whenever a moving object changes direction,
does not change the speed of an object,
acts at right angles to the velocity at any instant, and
is directed toward the center of a circle.
A centripetal force …
is the force that makes a moving object change direction,
is not a particular force, but the name given to the net force responsible for circular motion,
acts at right angles to the velocity at any instant, and
is directed toward the center of a circle.
Directions in circular motion:
Velocity is tangential (lies on a tangent to the path).
Centripetal acceleration and centripetal force are radial (point toward the center of a circle).
Centripetal acceleration and the object's velocity are always perpendicular.
Centripetal force and centripetal acceleration are always parallel.
______________
To put it in my own words:
It takes tangential force to create swing speed. Force with the same direction as the clubhead. The centripetal force that we have to produce to keep the club swinging is an effect of the velocity introduced by tangential forces. It is an effect of swing speed and not a cause.
For simplicity, assume a one-lever system (no lag pressure between hands and club).
To analyze what the pull from a left shoulder on a one-lever system does to the swing, the pull should be decomposed into two force vectors; One centripetal force component - pointing at the swing centre. And one tangential component that points in the same direction the swinging object is moving. The angle of the lever vs the angle of the centripetal force (the line from MOI to the swing center) provides all the info we need to estimate the tangential force.
The tangential component is the one that increases the swing speeed. It adds velocity energy to all the moving parts of the swing. The centripetal component changes the speed simply by changing the direction of the movement. The velocity energy of the system is not affected by this.
Applying only centripetal force is the same as hanging the lever assembly around your neck and just stand still. In a perfect, friction free and without earth gravity world , it will spin forever at a constant speed. Of course you will have to apply tangential force initialy to get the spin rate up.
We can do the same analyzis on a two-lever system from the hands and down; The hands pullling the club will induce a drag force* on the club. This drag force can be decomposed in a tangential component and a centripetal component. More clubhead lag (the further the golf shaft points away from the neck) will mean a larger ratio of longitudunal /centripetal force.
The actual golf stroke is an harmonic blend of tangential force that builds speed and centripetal force that purely helps us store the speed that's already there. You need to apply a centripetal force of increasing size to account for the ever increasing energy that is accumulated by tangential force.
I think it is important to undestand that tangential force is the only kind that builds swing speed. Even though the force we feel the strongest just before impact is likely to be the centripetal force, it's the tangential forces that do the work. And those who hit the ball long applies more of it than most others.
There is a lot of complicated things going on in the golf swing. The hand radius changes, the clubface radius changes etc etc. Looking for energy accumulation and release in the swing simplifies IMO some of the most basic mechanical understanding of what's going on. What it all boils down to then is that tangential forces are the only ones who add energy. We can use centripetal acceleration to store the energy in a circular move and we can use a few "tricks" to redistribute some of the energy towards the clubhead just prior to impact etc. But all the energy that eventually is transmitted to the ball comes from tangential forces.
I believe there's a lot of confusion between cause and effects here, also among experienced instructors. The major part of the strong pull that we feel from "pulling the rope" through impact is actually a simple reaction to the energy that's already accumulated in the swing. And the other part - a much smaller one - does in fact produce tangential force. But only as long as we're pulling from a point that is offsett the swing center.
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* When the right hand PP's work on the club below the left hand / club hinge - there will in addition be imposed a Newtonian moment on the club ref my first post in this thread - a momoment that will energize the spring effect of the shaft & clubhead. This energy will be stored and released later when the moment is reduced.
1) "I agree that the lag pressure point is driving the club. And by "driving" i mean adding energy to the club."
How does PP#3 add energy to the club considering that PP#3 is simply the right index finger against the back of the club?
2) "The point is that centripetal force doesn't add energy to the golf swing. It only stores the energy that has been added through the work of tangential forces."
How does a centripetal force store energy? Stored where? To what purpose? Is that energy eventually released? When, and how?
3) "The centripetal force that we have to produce to keep the club swinging is an effect of the velocity introduced by tangential forces."
Why is a centripetal force needed to keep the club swinging? You then immediately state that centripetal force is an "effect" and the "cause" of that effect is the "velocity produced by tangential forces". From where is this tangential force derived? When those tangential forces act to increase velocity - velocity of what? How does velocity of "what" produce a centripetal force?
4) "The tangential component is the one that increases the swing speed. It adds velocity energy to all the moving parts of the swing. The centripetal component changes the speed simply by changing the direction of the movement". How does a change in direction increase swing speed? Speed of "what"?
5) "More clubhead lag (the further the golf shaft points away from the neck) will mean a larger ratio of longitudunal /centripetal force."
Why? If the club lag is 90 degrees, why is there a higher ratio of longitudinal/centripetal force compared to a situation where the clubhead lag is 75 degrees?
6) "The actual golf stroke is an harmonic blend of tangential force that builds speed and centripetal force that purely helps us store the speed that's already there. You need to apply a centripetal force of increasing size to account for the ever increasing energy that is accumulated by tangential force."
Where does the centripetal force store the speed? If one uses a tangential force to move "what" why is energy accumulated? If the swinging "what" travels at a faster speed, why must centripetal force increase?
Somehow for some unknown reason I knew Bernt was gonna cop this ...love the note on the end in brackets.What Jeff really meant was ..since he is a physics expert himself ..is that you have just wrote a whole lot of bs..entertaining stuff
To understand a person's viewpoint, I need very simple explanations where every sentence is well-defined in terms of definitions and concepts, and where all the sentences are carefully connected so as to finally produce a coherent storyline.
Here is a photo of a golfer's clubhead swingarc.
One can see that the clubshaft/clubhead moves down-and-out-and forwards along a circular arc in the downswing. Therefore, the forces needed to move the clubhead need to achieve two goals from an energy perspective - i) move the clubshead at a finite speed in space and ii) move the clubhead in a circular arc (which is equivalent to supplying the clubhead with centripetal acceleration while it is traveling at its finite speed).
I would like to see Bernt use that simple model to describe the forces needed, and their mechanism of energy storage and release.
I would like to see Bernt use that simple model to describe the forces needed, and their mechanism of energy storage and release.
Jeff.
First you need tangential forces to make the club move at all. Then you need more of the same to get proper swing speed.
At the same time you need centripetal force to make the club move in a circle instead of flying down the driving range.
You should also be aware that the centripetal force is not a force per se in the golf swing. Because there isn't anything in there that is pulling from the swing center. The centripetal force is merely result of decomposing the total force on the club in a centripetal component and a tangential component - and possibly other components too - that will will reduce the quality of the stroke.
Hybrid Mode
