It sticks out my mind that GD used the Viper digital movie camera. Not sure of the frame rate they used but super high like the retail price which is around one million dollars. The viper has a mechanical shutter for a more film like look with no blur.

I wouldnt be surprised if the Nike commercial was shot on the Viper too. The Red camera which is out now wasnt around at the time of its shooting I dont think.

Any body work for Panavision out there?

First time trying to attach photos so hopefully this will work.

Jeff, I am no LD expert, just a humble amateur. These pictures of me were taken in October 2008 by GolfGuru. I think they were taken up around the shutter speed you wanted on his Casio F1 camera that can take bursts at up to 1200 fps I believe.

Bugger, not sure I uploaded them. Idiots guide please?

Regarding getting a frame at impact - I was just pointing to the one issue (especially seen when taking a divot) where the clubhead slows during impact and the shaft bends back - once the ball leaps off the face - the clubshaft springs forward.

Yes, of course. The divot/clubhead collision vs the tee'd ball/clubhead collision. One causing more shaft deflection than the other.

If he's got the F1 then the still bursts are up to 60 frames per second. High speed movies on the other hand can make it to 1,200 fps. Although here I think fps stands for "fields per second". Apples and oranges. Film movie cameras would still be "frames per second" having a mechanical shutter and a true film frame

My Casio FH20 has a burst of still photos up to 40 fps which are far clearer than 280 fps in digital movie mode for some reason. No shaft blur what so ever. (The faster fps movie settings require a ton of light and are smaller files, despite the blur I find 280 to be the best rate.)

And yes in burst mode the shaft looks like a very in focus bent snake while in movie mode it seems a rather straightish looking blur. This when regarding the same person doing the same shot one after the other.

If this shaft deflection is an anomaly of high speed still photography then Hogan might have been wrong to change shafts after reviewing his photos for Power Golf. Ill let the sharpness of the focused still bursts rule and chose to think that Mr Hogan and Mr Kelley had it right. The shaft is a snake.

O.B.

This is might be the best example of shaft deflection with high speed video.
Go to the 3:30 mark of this clip of Zuback.

Snake Handler
 

Here are four photos O.B. Left took at Cuscowilla in our private sessions last month. They illustrate his points . . . and mine. Also, they give insight into the 'Shaft Bend' questions Mike O. asked above. FYI, these are Stiff shafts -- not Super Stiff or Tipped -- but they are Stiff (and not of the 'Super Senior' variety :laughing9 ) .



Downstroke





Release





During Release





Impact Interval

Readers who wish to enlarge can click on the thumbnails below. Left click and use the 'pg up' and 'pg down' keys to navigate between the photos.

:salut:

Yoda

In your series of photos, I can see a phenomenon that I have seem many times previously. Before release, the clubshaft is bent backwards and after release the clubshaft is bent forward.

The question becomes - how does one interpret this phenomenon. I personally believe that there is a shaft flexibility issue and a shaft elastic recoil issue in play that disrupts the 100% irefutable causal relationship between the hand thrust action (cause) and the clubhead's sweetspot movement in space (effect). I can picture an S-shaped clubshaft that is 100% rigid, where one can essentially ignore the strange snake-like shape of the clubshaft, and where there is still a 100% correlation between hand thrust forces (cause) and the clubhead's movement in space (effect). However, when a shaft becomes increasingly flexible then I believe that there can be a time-lag phenomenon where hand thrust forces do not have an immediate effect on the clubhead and where one cannot simply imply that a straight line drawn between the hands and the clubface sweetspot at any time point in the downswing accurately represents the reality between "cause" (hand thrust forces) and "effect" (movement of the clubhead's sweetspot in space).

I watched Jason Zuback give an exhibition as a long-drive competitor and as a trick shot artist. He had a special ultra-flexible shaft that could bend into a C-shape. When he swung with that rope-like club he could hit the ball >250 yards - but only if his timing was perfect. He had to get the rope-like clubshaft to become straight at impact - so that the clubhead became like a flying object perfectly timed into impact. However, during the downswing, the clubhead was lagging behind his hands by a variable amount that varied considerably from swing-to-swing, and therefore there was no clearcut relationship between effort and effect (clubhead's sweetspot movement in space) until impact.

Jeff.

Deja Vu All Over Again
 

Jeff,

As I've already explained twice in this thread, the Clubshaft is responding to the Sweetspot's Centrifugal Line of Pull. It is NOT creating it (as you continue to insist). In fact, this 'bass-ackwards' thinking is your fundamental error.

The Sweetspot is orbiting, and in so doing, is creating a Centrifugal Force (Clubhead Inertia resisting a change in its direction). The Clubshaft is supplying the Centripetal Force that enables that orbit.

In performing its function, the Clubshaft is stressed at the Top (Lag Loading / 7-19). This is the true Clubhead Lag, i.e., the Sweetspot seeking to maintain its in-line condition with the Pressure Point Pressure and thereby creating Shaft Stress. It is no less than the Secret of Golf (6-C-2-0/A). Ideally, this Stress is never 'Released'.

[And while I'm here: This Shaft Stress is not Accumulator Lag, i.e., the out-of-line condition of the Left Arm and Clubshaft -- that you misidentified as Clubhead Lag by reference to Photo #1 in your post #118 -- which is Released. ]

Where was I? Oh yes . . .

Centrifugal Force (Swinging) or Muscular Thrust (Hitting) is driving the Clubhead.

Not the Clubshaft.

I am not saying that Clubshaft properties -- materials, flex, etc. -- are not important. They are. But, not in the ways so often promoted. And . . .

Not in the way described by you.

:salut:

BTW, you state that you see in my photos a "phenomenon that [you] have seen many times previously. Before release, the clubshaft is bent backwards and after release the clubshaft is bent forward." Question: How do you explain "The Snake" (Photo #4 in my post #127 above), where "after release", the Shaft simultaneously is bent both backwards and forwards?

:scratch:

Please include the photo in your reply, and for the visually-challenged among us, please trace the Shaft with a yellow line. Thanks!

Whirling Rocks and Straight Strings
 

Trust me, Jeff, that rope being swung by Jason Zuback had no trouble staying straight. If you had some footage of that event, I'm confident your 'captured images' would attest to that. Swing a pen knife 'round and 'round on a string, and you'll get the idea.

Of course, you lose certain advantages, e.g., the rope acts as an Impact Cushion (6-C-2-C) and also, Clubface Control becomes problematic (at the very least, this True Swing procedure demands a precise Ball Location). In fact, the whole drill sounds to me like a good argument for stiff shafts.

:salut:

Can I hit a perfect shot with this kind of shaft? :eyes:

Yoda - you wrote-:

"As I've already explained twice in this thread, the Clubshaft is responding to the Sweetspot's Centrifugal Line of Pull. It is NOT creating it (as you continue to insist). In fact, this 'bass-ackwards' thinking is your fundamental error.

The Sweetspot is orbiting, and in so doing, is creating a Centrifugal Force (Clubhead Inertia resisting a change in its direction). The Clubshaft is supplying the Centripetal Force that enables that orbit."

I appreciate your input, but I have a different explanation for observed events.

I agree that the clubshaft is not creating the centrifugal line of pull. (The clubshaft is creating another force - which I will explain later).

I think that you are wrong to state the clubshaft is supplying the centripetal force. The CP force is created by the hands holding the clubshaft, and the clubshaft is simply the connecting structure between the clubhead and the hands.

Here is my explanation. I created this model.



Imagine that a person is twirling a ball (attached to a piece of string) around his head. Imagine that he grasps the string between his right index finger and his thumb in a pincer grip and imagine that he holds his right hand vertically above his head and moves his right hand in a constant small circular motion. That circular motion is represented by the small inner circle.

Imagine that the string length is 18" and the red ball is attached to the end of the string.

The ball will travel in a constant circular path (represented by positions 1 and 2 and 3). The CP pull is exerted by the hands and the pull is along the length of the string and the CP force is at right angles to the ball position (right angles to a tangent at the circumference) at any point in time. The ball wants to travel in a straight line (at a 90 degree tangent to the circumference of the circle) at every moment in time, but it is prevented from that action by the CP force that is directed towards the center of the circle. The string transmits the CP pulling force from the ball to the hands (inwards pull towards the center). The string doesn't create the CP force. The ball travels in a perfect circular motion because the CP force (directed inwards towards the center via the string) balances the CF force (hypothetical outward -directed force).

Now consider placing a 6" long rigid structural object (that could be made of metal or rigid plastic) between the ball and the hands. The string length would now be reduced to 12" and it would be attached to the central end of that 6" structure which has a snake-like shape. The presence of that rigid structure, and its snake-like shape, would have no effect on the ball's path in space. The ball would continue to travel in a circle (position 4) and its motion would only be dictated by the CP force exerted by the right hand's circular twirling motion. The 6" structural unit would have no effect on the ball's path of motion - despite its snake-like shape.

Now consider what one would have to infer if the ball suddenly appeared at position 5 or 6 - where the ball is no longer on its circular path. One would have to infer that another force is at play that affected the ball's "expected" position.

That is what I believe is happening in those photographs. I believe that there is a CP force exerted by the hands on the grip end of the club. However, I believe that there is another force (derived from the flexible clubshaft's elastic properties) that kicks the clubhead off its CP-induced orbit. In other words, when I look at Jamie Sadlowski's clubhead post-impact in this next photograph - I believe that the clubshaft's flexibility (elastic properties) is causing a displacement of the clubhead off its "expected' orbit ("expected" in the sense of the clubhead only being propelled by the CP force passing through the clubshaft from the hands-to-the-clubhead).



If the clubhead was in that position only due to the CP force, then a straight line drawn between the hands and the sweetspot should be perpendicular to a tangent line drawn at the clubhead's position on its circular orbit. However, that straight line is not perpendicular to the clubhead's circular orbit in space. I think that the clubhead is equivalent to being at position 6 in my orbiting ball-on-a-string model.

Jeff.

KOC

That clubhaft-shape should not affect one's ability to execute a perfect shot - if the shaft doesn't provide an additional force that interferes with the CP-CF force relationship between the hands and the clubhead.

Jeff.

Gravity and Satellites
 

Oh, please, Jeff.

Try swinging the Clubhead without the "connecting" Clubshaft. Let's see what kind of orbit you can create.

:salut:

Yoda - you wrote-: "Trust me, Jeff, that rope being swung by Jason Zuback had no trouble staying straight. If you had some footage of that event, I'm confident your 'captured images' would attest to that. Swing a pen knife 'round and 'round on a string, and you'll get the idea."

Jason had a lot of trouble keeping that flexible shaft straight at start-up - as one would when dealing with a pen-knife attached to a string. When the penknife is already in a state of circular motion, the string would definitely be straight. However, if the penknife was stationary at start-up, it has inertia, and when the penknife is first pulled by the the string, the string is not in a perfect straight line relationship between the hands centerpoint-of-rotation and the penknife. Jason's clubhead lagged far behind the hands and the flexible shaft was always curved until the clubhead's speed reached a certain level of speed that could then produce a CF that could balance the CP-force exerted by the hands. From that point onwards, the clubshaft was straight.

Another point - when Jason's timing was off the clubhead bypassed his hands in a flipping motion near impact, and the flexible clubshaft was no longer straight. That happened especially if his hands slowed down just prior to impact.

Try swinging a penknife at the end of the string and then abruptly stop the hand motion - the string will not remain straight and the penknife will no longer remain in its circular orbit!

Jeff.

Yoda - you wrote-: "Try swinging the Clubhead without the "connecting" Clubshaft. Let's see what kind of orbit you can create."

I could retort - try swinging the clubshaft without the hands moving along a circular path and see what kind of clubhead orbit one can create.

Jeff.

do we have to have jeff?
 

can't jeff go and start his own web site and leave us alone? who gave him his own place here?

Clarifying statements regarding the string-ball example.

When I state that an additional force can throw the ball off its orbit, the force doesn't come from the string. The force can occur when the hands do not constantly move along a circular path at a smooth rate of speed - which provides the centripetal force. So, the following factors can disrupt the ball in its orbit.

1) Sudden hand over-acceleration movement (equivalent to Hk's over-acceleration idea).
2) Sudden hand deceleration movement (equivalent to quitting on the shot).
3) Hand motion becomes non-circular (equivalent to HK's steering idea).
4) Sudden change in the radius of the hands' circular motion (which causes a sudden non-circular motion as the hands move to an orbit of different radius).

Also, when I state the clubshaft's flexibility causes the clubhead to move off its orbit, I mean that it allows it. The fundamental cause is the slowing of the hands pre-impact, and the shaft flexibility allows the clubhead to move out of its perfect circular path.

Here is a strobe photo of Bobby Jones swing.



What causes the clubhead arc to be circular? The answer - the circular motion of the hands. Anything that disrupts the smooth circular motion of the hands (over-acceleration, quitting, steering) will disrupt the clubhead's circular motion. An overly flexible clubshaft only makes these problems more apparent.

Jeff.

Yes cause he is entertaining..personally i use the right gonad as pivot center

John

You wrote-: "who gave him his own place here?"

The answer is obviously Yoda. He made that decision independently. I suddenly found this "Golf By Jeff" section recently. If he wants to remove this section from his website at any time, he doesn't need anybody's permission because it is his website.

While this "Golf By Jeff" section exists, I will ask questions, freely debate issues, and never personally insult any forum member (by means of an ad hominem attack) for harboring a contrary point of view.

Jeff

Debate or Review...
 

Jeff,

A question for you. Do you believe in 10-23 different hand path?

KOC - I don't really believe that the hands ever move in a straight line in a full golf swing. The hands obviously move in an U-shaped arc and during the "straight section" of the U-shape, the radius of the hand arc's circular motion is so large that it appears "straight".

Jeff.

johnny, he has some sort of ocd i reckon!

Pistol:

You said - "Personally I use my right gonad"

What advantage do you consider you have over left gonad centered swingers/hitters and do you feel this is why female golfers hit the ball nowhere?

If you want the hands to move in a constant consistent arc . . . then why would you want to move off the ball???? That's the WHOLE POINT OF THE CENTERED PIVOT . . .

Styles
Being from a windy area ..my left side is very dominant so its just a feel thing ..the right gonad evens me out so the actual pivot center is between..perineum lol
Do women play golf?

12PB

You wrote-: "If you want the hands to move in a constant consistent arc . . . then why would you want to move off the ball???? That's the WHOLE POINT OF THE CENTERED PIVOT . . ."

When I stated a "constant consistent arc", I only meant a hand arc that is smooth without any sharp, abrupt (V-shaped) curves. I didn't mean a very rounded hand arc. The hand arc actually shouldn't be too rounded because that predisposes to a sweep release. To get a late release, like Sergio Garcia in the next photo, the hand arc must be distinctly U-shaped with a tight curve at the lower end of the U-shape (equivalent to going around a small pulley at the end of the endless belt).



I also have never recommended a non-centered pivot. I wrote a review paper on weight shift in the golf swing and I used the following diagram in that paper.



Image 1 shows a "hypothetical" perfectly centered pivot where the golfer rotates around an imaginary central axis (dotted line). The head is central, the spine is vertical and the golfer simply pivots around the central axis. However, that would only be possible if human beings had only one leg which was in the center of the pelvis and perfectly in line with the spine.

The reality is that human beings have two legs and a golfer has to pivot over the right leg in the backswing and over the left leg in the downswing, which means that there are really two pivot axes for the pelvis in a golf swing. There are biomechnaical consequences to this biomechanical fact.

One can choose to keep one's head centralised (in a tripod fashion) and then pivot centrally => that prediposes to a left-centered pivot action where the spine will tend to lean leftwards at the end-backswing (slight reverse pivot).

Alternatively, one can adopt a small amount of rightwards spinal tilt at address and allow the head to move slightly to the right-of-center of the stance. That allows a golfer to acquire secondary axis tilt naturally during the backswing pelvic action (which moves the lumbar spine left-laterally and aligns the lumbar and thoracic spine into a "straightish" spine that is tilted to the right at the end-backswing.

By my arbitrary personal definition, both a leftwards-centered pivot action and a rightwards-centered pivot action are centralised swing actions - because the head remains within the inner boundaries of the feet and there is no unnecessary lower/upper torso swaying movements off the ball.

Jeff.

Sergio is RIGHT ON TOP OF THE BALL . . . actually looks like your hypothetical left pivot . . . exactly my point . . . thanks for putting that up. I don't see no reverse k in that pivot either . . . perfect. Probably known as the best ball striker on tour . . . pivot is a big reason.

slo hand (not clapton)
 

That a real golf swing in that add?

Certainly no hands slowing going into impact there...

(bobby jones's driver swing either for that matter)

12PB

I agree that SG is a great ball striker. However, I would not automatically conclude that it is primarily due to his having a leftwards-centered backswing action. He has many other great golf swing skiils.

I also don't mind if you prefer a leftwards centered backswing action. Sam Snead and Mike Bennett and Aaron Baddeley (new swing) use that type of backswing action to great effect.

However, other great golfers - Tiger Woods, Ben Hogan, Anthony Kim - use a rightwards-centered backswing action with great results.

Jeff.

'Round and 'Round We Go
 

Jeff,

Assume a tethered ball in orbit around an axis. Does the tether (and its tension) serve as the centripetal force of that action? If not, what does? If so, how does that differ from the concept of the clubhead tethered to its center (left shoulder) by the left arm and clubshaft?

:)

Yoda - that's a very good question.

Consider this diagram - from Wikipedia.



Imagine a ball tethered to the center via a piece of string and consider the ball in motion. Ignore how the ball got into motion. In other words, ignore the forces that provide energy to keep the ball in constant motion. While the ball is in a state of constant circular motion, the centripetal force keeping the ball moving along a circular path passes through the taut string that tethers the ball to the center point of string attachment.

A good analogy would be looking at the club's behaviour after release of PA#2. At that point, no further energy is inputted into the system and the club is freewheeling in space. If the clubhead follows a circular path (like the ball on a string) then there must be a centripetal force passing through the clubshaft and straight left arm to the fulcrum point (left shoulder socket).

However, consider the clubhead's movement before release. If the clubhead follows a circular path, and the clubhead cannot generate energy independently within itself, then it must be responding to energy derived from the golfer's hand movements in space. The same applies to the orbiting ball. If there is no independent energy source within the orbiting ball, then "something" must be supplying the energy to make the ball keep on moving around in a circle. The energy source is the movement of the index finger and thumb holding the end of the string. To make the orbiting ball keep on moving endlessly in a circle, the hand motion must have a twirling-circular quality where the movement of the hand in its inner circle arc of rotation travels at roughly the same rpm (but different surface speed) than the orbiting ball. If the orbiting hand (in its inner circle rotational motion) abruptly slows down, or abruptly speeds up, or moves in a non-circular manner, then it will immediately disrupt the circular motion of the orbiting ball. In other words, to keep the tethering string taut and to allow the tethering string to apply a constant/unwavering centripetal force directed at the center of the circle of the orbiting ball (and orbiting hand), the hand must keep on moving in a circular fashion. That's the analogy I use for the golf swing - when I state that the hand arc motion must have a circular quality. If the hand arc's motion was constantly along a straight line (and in no sense circular) then how could the clubshaft and clubhead ever travel in a circular arc?

Jeff.

Mandrin!!! What's up man!

Not ready to let you put Hogan in that list . . . we can find swings indicating otherwise . . . Hogan did EVERYTHING.

Dating Game
 

Jeff,

You have made two statements that are in direct conflict:

Behind Door #1:

"The CP pull is exerted by the hands and the pull is along the length of the string . . . "

Behind Door #2:

"The string transmits the CP pulling force from the ball to the hands (inwards pull towards the center)."

So which is it, Jeff?

Does the hand -- it really should be singular as defined by your model -- create the CP pull (hand to ball) or does the ball create it (ball to hand).

Hint:

We need a third door.

We are concerned here with a mass orbiting about an axis of rotation and exhibiting both a centripetal force (a force 'seeking the center' and whose origin we are now debating) and a centrifugal force (a force 'fleeing the center' and that is reactive to the centripetal force). An orbiting mass constantly accelerates towards its axis of rotation. This centripetal acceleration demands an equal and opposite force that opposes the centripetal force and creates an outward centrifugal reaction directed away from the axis.

In your model, the ball is the orbiting mass and the hand is the axis of rotation. The hand is not the centripetal force (as you incorrectly state). It is, after all, the axis! Instead, the centripetal force (acceleration) is exerted on the ball by another object (in your model, the string). Then, the centrifugal reaction is exerted by the ball on the object that originated the centripetal acceleration (the string).

The string, Jeff.

The string.

:golfcart2:

Yoda - I think that this debate is getting unnecessarily complicated and unproductive.

I think of it this way.

The orbiting ball receives all its energy via the string. The source of the energy is the hand moving in a circular manner. The energy travels outwards from the hand to the orbiting ball- along the string. That energy is required to perform two roles - i) keep the ball moving at a constant speed and ii) keep the ball moving in a circle at its constant surface speed.

When a orbiting object travels at a constant speed it may not need much energy to keep it moving at a constant speed (if there is little frictional resistance to its movement in space), but it requires constant energy input to constantly change direction (in order to move in a circular path). In other words, although the orbiting ball is traveling at a constant surface speed, it needs a constant source of energy to centripetally accelerate (accelerate towards its center of rotation). That energy comes from the hands and it is transmitted via the connecting string.

If you understand that viewpoint - then door 1 is correct.

Door 1

Behind Door #1:

"The CP pull is exerted by the hands and the pull is along the length of the string . . . "".

However, one can look at this orbiting ball scenario from a different perspective, and look at the scenario from the orbiting ball's perspective. Then door 2 applies.

Door 2

Behind Door #2:

"The string transmits the CP pulling force from the ball to the hands (inwards pull towards the center)."

The ball experiences a centripetal force that pulls it towards its center of rotation. The pull is in the direction of centripetal acceleration. The ball doesn't know where the CP force is coming from - it only knows that it is being pulled by the string, and it happily thinks that the string is providing a CP force that keeps it a state of constant centripetal acceleration.

However, ultimately the centripetal force that keeps the orbiting ball traveling in a circle is derived from the orbiting hand's movement in space, and the energy must travel from the hands to the ball - travels outwards along the string. Some of that energy makes the ball move, and some of that energy supplies a centripetal force that conceptually travels back down the string and keeps the orbiting ball from flying into space. I find it meaningless to think of the string providing that CP force - because the string doesn't really create energy. It only allows part of the energy created by the orbiting hands to be translated into a CP force that pulls the orbiting ball towards the center.

I actually try to avoid using the terms "centripetal" and "centrifugal" in my thinking about the golf swing. It gets way too semantic and too complicated. The idea of a centrifugal force is merely a conceptual idea used to see the CP force as being balanced by an equal and opposite force. Many people state that it not really a force - because it cannot exist alone. I am sympathetic to the idea that it is not useful to conjure up the idea of a CF working in the opposite direction to a CP force.

I much prefer to think in terms of vectors of movement and force, and not use the terms CP force or CF force if I can avoid the terms. That's why I like nmgolfers explanation of the release phenomenon.

See - http://perfectgolfswingreview.net/Ne...%20Science.htm

When I think of the golf swing, I never think of a rotational center. I simply see different body parts moving in 3-D space, and I simply think of the forces that move those body parts and their vector of movement. I think the same way with respect to the golf club. The golf club is only moved by pull-forces or push-forces exerted at grip level.

Jeff.

Here is another perspective on the orbiting ball situation.

I prefer not to even think of CP forces and/or CF forces.

I simply know that the hand moves in a small circle, and that the orbiting ball rotates in a larger circle, and that they rotate at the same rpm. I know that they are connected together by a piece of string. I know that the energy source is the hands (rotating in space). In that sense, the hands are pulling the ball via the string. I know that the orbiting ball follows a circular path because the hands follow a circular path, and that the string will remain taut if the hands move smoothly and at an even pace. I know that the whole system breaks down if the hands suddenly accelerate, or suddenly decelerate, or if the hands move in a straight line.

I don't need to invoke concepts of CP force or CF force to understand what is happening in this orbiting ball situation.

The same applies to the pivot. I don't need to think of a pivot center or a pivot axis. I simply think of how the body moves in 3-D space.

Jeff.

A Whole New World . . . A Whole New Different Point Of View!
 

:shock:

Jeff . . . this praise . . . coming from you . . . I'm not worthy. :notworthy But thanks anyway . . . you've made my day!

Buzzer Sound: EEEEEEEEEEEEEEEEEEEENNNNNNNNNNNNNNNHHHHH!!!!

Sorry, Jeff. :( Door #1 is not the correct answer. It never has been the correct answer, and it never will be the correct answer, despite your heroic attempts to obsolete every physics text ever written. Simply put, the axis of rotation is not the centripetal force. Try again . . .

Buzzer Sound: EEEEEEEEEEEEEEEEEEEENNNNNNNNNNNNNNNHHHHH!!!!

Sorry, Jeff. :( Door #2 is not the correct answer. The string doesn't transmit the centripetal force -- as you continue to maintain and would have us believe -- the string is the force! Try again . . .

Buzzer Sound: EEEEEEEEEEEEEEEEEEEENNNNNNNNNNNNNNNHHHHH!!!!

Sorry, Jeff. :( Attempting to divert the argument is poor tactics and just plain bad manners. Besides, the usual smoke and mirrors won't work here. Try again . . .


Bad idea. :nono:

Yes, I can see how such a simple approach might work. :rolleyes: After all, this whole centripetal-centrifugal thing is way too complicated. Especially when we're confronted with the truths taught in Physics 101. Best that we redefine the way the world works, right Jeff?

:salut:

mb6606

You sent me a link to this video of Jason Zuback's swing which has a number of slow mo sections.

http://www.youtube.com/watch?v=3Kp2J8gW1qw

I made the following series of images of his downswing



First of all, regarding the clubshaft. I see this problem of double images frequently - even when examining slow mo videos. This makes it difficult to know what is real versus camera distortion. Image 4 shows two images - one of the images has forwards shaft lean. Image 5 shows double images at impact with the shaft bent back in the one image, which would be expected post-impact.

I therefore do not know whether Jamie Sadlowski's forwardly bent shaft post-impact is "real" (possibly due to using a more flexible shaft) or due to camera distortion.

Secondly, look at Jason's swing. He has a centralised pivot action, and he reverse pivots slightly with a large hip turn (like Sam Snead) by the end-backswing - image 1. Note how he then has to reverse his spine tilt in the downswing so that he acquires a rightwards tilt-secondary axis tilt in the early downswing - image 3. I don't think that it is a biomechnaically efficient action. Note how he loses his clubhead lag angle - image 3. I think that it is due to the fact that he has to throw his upper torso and therefore arms backwards (away from the target) at the start of the downswing to reverse the spine tilt. The reversal of hand movement (going backwards away from the target) predisposes to an early release.

Here is another example of that phenomenon in an excellent golfer.



In the first swing, he reverse pivots slightly. Note his loss of clubhead lag angle. In his second swing I think he has a better pivot action with a reverse-K look, and a much better retention of his clubhead lag angle in the early downswing.

That's why I prefer Jamie's swing over Jason's swing. Jamie has a traditional swing with a reverse-K look at the end of his backswing, and he retains his clubhead lag angle well into the downswing.

Jeff.

Yoda - I have been deciding whether to respond to your last post. Your tone is demeaning and ill-conducive to an ongoing debate. Why can't you simply state your disagreements without pontificatiing, and implying that you are the final arbiter of the "truth"?

I don't think that you understand my perspective.

I will rephrase it.

The hand's movement is the source of energy that gets the ball to move in space. The string transmits that energy to the ball by means of a continuously taut string - any hand movement in a circular manner causes the ball to move in a circular manner (at the same rpm but along a wider circle of greater radius). The energy imparted to the ball gets the ball to perform two actions - i) acquire a surface speed of a finite value; and ii) centripetally accelerate - which merely represents a constant change in direction so that the ball follows a circular path.

The string is continously taut. That is necessary to counteract the tendency of the ball to fly away (due to centrifugal forces). Therefore, you are correct to state that the taut string represents the centripetal pull towards the center to counteract the tendency of the ball to fly away in a straight line direction at a tangent to the circle. However, the centripetal pull is not created by the string - the string is merely reactive to the dynamic situation of an orbiting ball that has acquired enough energy to fly away unless the string remains taut and provides a centripetal pull towards the center.

My personal perspective is focused on the following facts.

1) The source of energy for the orbiting ball is the continuous movement of the hand in a circular motion.
2) The hand constantly pulls the orbiting ball via a taut string - so that the orbiting ball revolves at the same rpm as the hand.
3) The ball acquires motional energy from the hand via the taut string, and this energy includes a centrifugal tendency which requires an equal counteracting centripetal pull by the taut string to ensure that the orbiting ball moves in a circular orbit.
4) It is true that the taut string is a constant reflection of the centripetal pull towards the center. However, the string doesn't independently create that centripetal force. The centripetal force only becomes necessarily operant because the ball has acquired motional energy from the motion of the hand that would cause it to fly off into space unless there was a centripetal pull from the taut string to counteract/equalize that centrifugal tendency.

Jeff.

Tough Love
 

Yes, Jeff, I suppose my post was a bit much. But, you know what? For some reason, you inspire that in me!

Oh, and I completely understand your perspective on centripetal force, both from the 'hand's' point of view (Door #1) and the 'ball's' point of view (Door #2). Goodness knows you've spent enough time educating me. And your writings do indicate that you understand the essence of the forces involved. Yet, you then totally deep-end and restate to your own end basic laws of physics that have been accepted since the time Isaac Newton wrote his Philosophiæ Naturalis Principia Mathematica (1687). You put up a lot of good stuff, Jeff, but man, you make it difficult to sit idly by as you reinvent concepts that have served mankind well for centuries.

To me, that's arrogance.

And when I see it, I call it.

Then again, that's why I've created this Golf By Jeff Forum and given you domain. Here you can pick things apart to your heart's content and enjoy relative freedom from my comment. But, it's also why I've put a 'caveat emptor' sign at the front door and stated that your presence here does not imply endorsement of your opinions by LBG.

:salut: