A HELPING HAND

[golfbulldog]

Jim,

Yes, that is correct.

Inertial forces arise with acceleration. However, no thrust, no acceleration.

Sensing lag equals sensing inertial force/torque, hence acceleration.

What would one of these pressure sensitive resistors record if placed between shaft and PP3?

http://www.tekscan.com/flexiforce.htm

As hands slow down prior to impact for efficient transfer of momentum to clubhead - slower hands means deceleration and less lag pressure at impact ?

can this lag pressure be sustained ? without some muscle force in right forearm continuing to accelerate the pp3 against shaft even after impact?

 

[mandrin]

Each golfer a kingdom unto its own

What would one of these pressure sensitive resistors record if placed between shaft and PP3?

http://www.tekscan.com/flexiforce.htm

As hands slow down prior to impact for efficient transfer of momentum to clubhead - slower hands means deceleration and less lag pressure at impact ?

can this lag pressure be sustained ? without some muscle force in right forearm continuing to accelerate the pp3 against shaft even after impact?

golfbulldog,

There are scientific studies pertaining to the interfacing of hands and clubshaft. Just can’t remember anything precise about them.

I seem to remember however that the pro type quality golfers had hardly any pressure exerted by trail hand through impact and quite the opposite for amateurs. But could be wrong. Poor memory.

I am quite sure that any possible study will reveal that the hand shaft interface forces to be a highly individual matter and very likely often not agreeing with golfer’s feel.

One very important element of any swing is to have the hands slightly ahead of the clubhead at impact, and that is perhaps what is primarily important playing attention to pressure points #1 and #3.

 

[Biffer]

mandrin said " One very important element of any swing is to have the hands slightly ahead of the hands at impact, and that is perhaps what is primarily important playing attention to pressure points #1 and #3."

Did you mean to say that, at impact, the hands should be slightly ahead of the clubhead? Or, at impact, the hands should be slightly ahead of where they were at address?

 

[golfbulldog]

golfbulldog,

There are scientific studies pertaining to the interfacing of hands and clubshaft. Just can’t remember anything precise about them.

I seem to remember however that the pro type quality golfers had hardly any pressure exerted by trail hand through impact and quite the opposite for amateurs. But could be wrong. Poor memory.

I am quite sure that any possible study will reveal that the hand shaft interface forces to be a highly individual matter and very likely often not agreeing with golfer’s feel.

One very important element of any swing is to have the hands slightly ahead of the hands at impact, and that is perhaps what is primarily important playing attention to pressure points #1 and #3.

I agree with hands ahead of ball at impact but less inclined to agree with theory that pros feel little lag pressure at impact. Whilst lag pressure is a subjective feel, there must be a greater passive pressure exerted by the shaft against pp3 in a swing where the clubhead trails the hands ( lagging) rather than a swing where the clubhead leads the hands ( flipped). It may be less pressure than they felt at transition when inertial forces were greatest ... but it will not be zero pressure.

I say "passive" to try to distinguish the tight grip pressure between thumb, shaft and pp3 that a flipper might adopt to hold onto the club post flipping.

What do you think of Brian's Lag pressure drill - thumb off the shaft - passive pressure only exerted by trailing clubhead onto pp3. No thumb to provide opposing active pressure in holding onto a flip - therefore have to pivot correctly and sustain lag??

I know you are getting alot of questions but this is a key concept ( lag ) for anyone who follows Homer , either to the letter or in general broad theory.

Thanks Mandrin

 

[mandrin]

I agree with hands ahead of ball at impact but less inclined to agree with theory that pros feel little lag pressure at impact. Whilst lag pressure is a subjective feel, there must be a greater passive pressure exerted by the shaft against pp3 in a swing where the clubhead trails the hands ( lagging) rather than a swing where the clubhead leads the hands ( flipped). It may be less pressure than they felt at transition when inertial forces were greatest ... but it will not be zero pressure.

I say "passive" to try to distinguish the tight grip pressure between thumb, shaft and pp3 that a flipper might adopt to hold onto the club post flipping.

What do you think of Brian's Lag pressure drill - thumb off the shaft - passive pressure only exerted by trailing clubhead onto pp3. No thumb to provide opposing active pressure in holding onto a flip - therefore have to pivot correctly and sustain lag??

I know you are getting alot of questions but this is a key concept ( lag ) for anyone who follows Homer , either to the letter or in general broad theory.

Thanks Mandrin

Golfbulldog,

The body, shoulders and arms are heavy and rather predictable. The hands/wrists are very different indeed. They are extremely versatile and flexible nervous tools almost too much for a golf swing hence the advice by various golf instructors to use ‘dead’ hands.

One can have the arms either slowing down or accelerating and yet in both cases one can still have either a positive or a negative pressure on pp3. The wrist torque(s) is an independent parameter in the equation. Things are never really very simple in golf.

For an aspiring golfer I do agree that becoming acutely aware of the various pressure points provides an excellent feedback mechanism but yet excellent golf can be played not knowing anything about them. Brian’s lag pressure drill is an excellent way to become aware of lag.

 

[mandrin]

mandrin said " One very important element of any swing is to have the hands slightly ahead of the hands at impact, and that is perhaps what is primarily important playing attention to pressure points #1 and #3."

Did you mean to say that, at impact, the hands should be slightly ahead of the clubhead? Or, at impact, the hands should be slightly ahead of where they were at address?

Biffer,

Now we are really delving into details. I rather stick to science. All these practical details I prefer leaving them to the experts, doing this for a living. However you asked, so I will answer.

Impact is what it is all about. At that time address position is something already far in the past. Therefore what is important is hands ahead of the clubhead at impact.

Your question made me remember an interesting booklet by Ike S. Handy published in 1967 - “How To Hit A Golf Ball Straight”. He is very adamant about hands passing the ball ahead of the clubhead.

 

[mandrin]

What about this . . . The hands lose their speed before the club I think? So would the clubhead be still accelerating even though the hands aren't?
According to Homer Kelley the Pressure Points in the hands are Clubhead Feel (sweet spot) . . . so if we are to accept that premise (which maybe we shouldn't) would lag not still be present?

The hands lose their speed before the club I think? So would the clubhead be still accelerating even though the hands aren't?

The clubhead keeps accelerating till the in-line situation is reached, hence about impact. At that moment there is a transition from negative to positive acceleration for the hands/arms.

It is precisely the deceleration of the arms/hands which causes an extra bit of acceleration for the clubhead. It generously gives up part of its energy/momentum to the clubhead.

According to Homer Kelley the Pressure Points in the hands are Clubhead Feel (sweet spot) . . . so if we are to accept that premise (which maybe we shouldn't) would lag not still be present?

I don't quite get the question. Feel is a very slippery concept in golf. For instance when you sense impact, the ball is already gone since an eternity.

 

[rundmc]

The hands lose their speed before the club I think? So would the clubhead be still accelerating even though the hands aren't?

The clubhead keeps accelerating till the in-line situation is reached, hence about impact. At that moment there is a transition from negative to positive acceleration for the hands/arms.

It is precisely the deceleration of the arms/hands which causes an extra bit of acceleration for the clubhead. It generously gives up part of its energy/momentum to the clubhead.

According to Homer Kelley the Pressure Points in the hands are Clubhead Feel (sweet spot) . . . so if we are to accept that premise (which maybe we shouldn't) would lag not still be present?

I don't quite get the question. Feel is a very slippery concept in golf. For instance when you sense impact, the ball is already gone since an eternity.

I agree on the feel thing and the ball being gone . . . so I would say that it would be more important to feel the pressure all the way . . . because if you feel it go . . . it went WAY EARLIER than you felt it . . . . wouldn't that stand to reason?

Anyway . . . good thread! Thanks!

 

[mandrin]

I agree on the feel thing and the ball being gone . . . so I would say that it would be more important to feel the pressure all the way . . . because if you feel it go . . . it went WAY EARLIER than you felt it . . . . wouldn't that stand to reason?

Anyway . . . good thread! Thanks!

rundmc,

By the time you sense impact and can do anything about it the ball the ball has already travelled a distance of 30 to 40 ft.

 

[Biffer]

Details are important.

Quote:
Originally Posted by Biffer
mandrin said " One very important element of any swing is to have the hands slightly ahead of the hands at impact, and that is perhaps what is primarily important playing attention to pressure points #1 and #3."

Did you mean to say that, at impact, the hands should be slightly ahead of the clubhead? Or, at impact, the hands should be slightly ahead of where they were at address?
------------------------------------------------------------------------
Biffer,

Now we are really delving into details. I rather stick to science. All these practical details I prefer leaving them to the experts, doing this for a living. However you asked, so I will answer.

Impact is what it is all about. At that time address position is something already far in the past. Therefore what is important is hands ahead of the clubhead at impact.

Your question made me remember an interesting booklet by Ike S. Handy published in 1967 - “How To Hit A Golf Ball Straight”. He is very adamant about hands passing the ball ahead of the clubhead.

-----------------------------------------------------------------

mandrin,

Sorry, I should have highlighted that part of your statement about the hands. Just wanted to clarify, not nit pick. Thanks for answering.

Lary

 

[rundmc]

rundmc,

By the time you sense impact and can do anything about it the ball the ball has already travelled a distance of 30 to 40 ft.

Precisely my point about why sensing lag is important . . . if you feel that you have "thrown the club" . . . by the time you FEEL the throwaway . . . it happened about 2 or 3 feet before that (or whatever the distance).

 

[mandrin]

Quote:
Originally Posted by Biffer
mandrin said " One very important element of any swing is to have the hands slightly ahead of the hands at impact, and that is perhaps what is primarily important playing attention to pressure points #1 and #3."

Did you mean to say that, at impact, the hands should be slightly ahead of the clubhead? Or, at impact, the hands should be slightly ahead of where they were at address?
------------------------------------------------------------------------
Biffer,

Now we are really delving into details. I rather stick to science. All these practical details I prefer leaving them to the experts, doing this for a living. However you asked, so I will answer.

Impact is what it is all about. At that time address position is something already far in the past. Therefore what is important is hands ahead of the clubhead at impact.

Your question made me remember an interesting booklet by Ike S. Handy published in 1967 - “How To Hit A Golf Ball Straight”. He is very adamant about hands passing the ball ahead of the clubhead.

-----------------------------------------------------------------

mandrin,

Sorry, I should have highlighted that part of your statement about the hands. Just wanted to clarify, not nit pick. Thanks for answering.

Lary

Lary,

I see your point. I had not seen the typo. Misunderstood your question as a result. Thanks for pointing it out so delicately. .

 

[ThinkingPlus]

I Acknowledge My Mistakes

-------
Basically, since this is an elastic collision, momentum is not strictly conserved, but it is close enough for our purposes. You can also approximate Mclub with the mass of the clubhead alone since the impact interaction occurs over such a short time.

Newton's 1st Law
-----
Lag pressure maintained through impact will result in a collision that is more inelastic (less lossy) than if one had a clubhead moving with a constant velocity (my assertion, et al.).


In the first post it is clear that the clubhead is considered a free mass. (this is against TGM philosophy.) In the second post it is however just the opposite. An obvious and very clear contradiction in two adjacent posts.

Also in the first post it is stated that in an elastic collision momentum is not conserved. This is a gross error. Momentum is ALWAYS conserved, both in elastic and inelastic collisions.

Moreover in the second post it is stated that there is less loss in a more inelastic collision. This is a gross error. It is just the opposite. Kinetic energy is conserved in an elastic collision and is not in an inelastic collision.




I got my inelastics and elastics confused. I also made a mistake relative to conservation of momentum (was thinking energy). The statement about the clubhead acting as a mass on the end of a string is an assertion from Cochran and Stobbs. The 2nd statement was incompatible in mechanism, but the conclusion should be correct in that if the clubhead is accelerating at impact the post impact ball speed and clubhead speed will be greater than if the head was at constant velocity. This assumes the instantaneous velocity at impact was the same in both cases.

 

[mandrin]

I got my inelastics and elastics confused. I also made a mistake relative to conservation of momentum (was thinking energy). The statement about the clubhead acting as a mass on the end of a string is an assertion from Cochran and Stobbs. The 2nd statement was incompatible in mechanism, but the conclusion should be correct in that if the clubhead is accelerating at impact the post impact ball speed and clubhead speed will be greater than if the head was at constant velocity. This assumes the instantaneous velocity at impact was the same in both cases.

Steph, you don’t mind if I continue to point out errors.

Your statement above is a bit confusing. You admit that your 2nd statement was incompatible in mechanism and yet you maintain that the conclusion should be correct. I don’t agree. I have copied from Cochran & Stobbs the appropriate paragraph.

“An important consequence of the inability of the player to exert any positive influence on the ball during impact, is this: the only dynamic factor that matters in producing distance is clubhead speed. A given clubhead making square contact with the ball at 100 miles per hour will send it the same distance wether it is accelerating, slowing down, or moving at constant speed. It may conceivably help your game to feel you are accelerating through impact, in so far as it may prevent the common fault of reaching maximum clubhead speed too soon; ... But what is certainly not true is that acceleration of the clubhead into impact will produce any effect whatsoever on the ball beyond that produced by the pure speed at which it is traveling; and furthermore, in any full shot, acceleration through impact is a sure sign of wasted effort which could have been used to produce greater speed if it had been expended earlier.”

You will probably readily admit that this does not quite fit with your ideas about impact. Since you agree with Cochran & Stobbs that the clubhead virtually behaves like a free mass than you should accept also that you can' not exert any influence on the ball departure speed during the impact interval. Have a look at a post where I put forward some ideas.

Steph, I know it is a delicate matter since it is going against the believe system of TGM but I don't feel that science is to be made subservient to golf.

 

[ThinkingPlus]

I Don't Entirely Agree With C&S

Steph, you don’t mind if I continue to point out errors.

Your statement above is a bit confusing. You admit that your 2nd statement was incompatible in mechanism and yet you maintain that the conclusion should be correct. I don’t agree. I have copied from Cochran & Stobbs the appropriate paragraph.

“An important consequence of the inability of the player to exert any positive influence on the ball during impact, is this: the only dynamic factor that matters in producing distance is clubhead speed. A given clubhead making square contact with the ball at 100 miles per hour will send it the same distance wether it is accelerating, slowing down, or moving at constant speed. It may conceivably help your game to feel you are accelerating through impact, in so far as it may prevent the common fault of reaching maximum clubhead speed too soon; ... But what is certainly not true is that acceleration of the clubhead into impact will produce any effect whatsoever on the ball beyond that produced by the pure speed at which it is traveling; and furthermore, in any full shot, acceleration through impact is a sure sign of wasted effort which could have been used to produce greater speed if it had been expended earlier.”

You will probably readily admit that this does not quite fit with your ideas about impact. Since you agree with Cochran & Stobbs that the clubhead virtually behaves like a free mass than you should accept also that you can' not exert any influence on the ball departure speed during the impact interval. Have a look at a post where I put forward some ideas.

Steph, I know it is a delicate matter since it is going against the believe system of TGM but I don't feel that science is to be made subservient to golf.

I have never read C&S. I have received information 2nd hand from many people who seem to believe what C&S have to say. I therefore acknowledge that some of what they say may be correct. I don't agree with the statement you provided however. If the clubhead is accelerating at impact then dv/dt is non-zero (don't you just love redundant statements). If you believe that the ball<>clubhead momentum transfer (efficiency) is the same whether the clubhead is at a constant velocity or accelerating, then if dv/dt of the clubhead is non-zero, post impact it will be traveling with greater velocity than if dv/dt = 0. I would maintain that if the clubhead is traveling faster post-impact, then the golf ball would as well and that difference will be proportional to the momentum transfer efficiency times the change in clubhead velocity.

One of these days I will need to get their silly book and read it. Then I can judge for myself whether their methodology was sound. My understanding (2nd hand) is that they measured and analyzed the swings of good amateurs and professionals. While this gives substantial insight into how those players swung the club, it might not represent ideal. Maybe I'll kick out an order today for the book.

 

[mandrin]

persona non grata

I have never read C&S. I have received information 2nd hand from many people who seem to believe what C&S have to say. I therefore acknowledge that some of what they say may be correct. I don't agree with the statement you provided however. If the clubhead is accelerating at impact then dv/dt is non-zero (don't you just love redundant statements). If you believe that the ball<>clubhead momentum transfer (efficiency) is the same whether the clubhead is at a constant velocity or accelerating, then if dv/dt of the clubhead is non-zero, post impact it will be traveling with greater velocity than if dv/dt = 0. I would maintain that if the clubhead is traveling faster post-impact, then the golf ball would as well and that difference will be proportional to the momentum transfer efficiency times the change in clubhead velocity.

One of these days I will need to get their silly book and read it. Then I can judge for myself whether their methodology was sound. My understanding (2nd hand) is that they measured and analyzed the swings of good amateurs and professionals. While this gives substantial insight into how those players swung the club, it might not represent ideal. Maybe I'll kick out an order today for the book.

Steph, qualifying the concerted efforts of a group of respectable English scientists as silly without even having taken notice of their finding is not a very scientific attitude.

But you don’t have to buy the book by Cochran & Stobbs. All you have to do is to have a look at my post. Why don’t you try to refute my arguments, should be straight forward. I know it has to do primarily with conservation of momentum and you have shown some obvious weakness in this area but I can give you a hand if required.

Or if you feel that approach to be negative and like to be positive why not formulate your theory and calculate with it the significant increase in departure speed of the golf ball due to a force applied by the shaft onto the clubhead during the impact interval. Should be rather straight forward. I am really looking forward to your theory and calculations.

It is very comfortable to remain in the domain of vague philosophical statements but science is more about precision and about things which can be quantified. So give it a try knowing that you are risking becoming a persona non grata on your forum.

 

[golf2much]

Appreciate the helping hand.....

[SIZE=-2]Conservation of Energy is what happens at the ball.
Part1. Angular momentum is about what happens on the way to the ball. [/SIZE]

Very peculiar statements. The simple scientific truth is that effort expended by the golfer from the top creates motion and associated with it there is generated simultaneously kinetic energy and angular momentum. The angular velocities increase as the downswing proceeds and with it also the kinetic energy and the angular momentum.

[SIZE=-2]The longer you sustain the lag, the smaller the wheel, and like the ice skater pulling in her arms, the faster the clubhead mass must travel to conserve angular momentum.[/SIZE]

Angular momentum is not conserved in a golfer’s downswing since there is not any to be conserved to start with. It is being generated throughout the downswing by the effort expended by the golfer. Whilst being continuously generated it is redistributed due to unfolding of the club.

In Part2 impact interval is discussed and golf2much states that much of the kinetic energy of the clubhead is transferred to the ball and formulates this as:

[SIZE=-2](½ m1*v1^2 - losses) (clubhead) = ½ m2*v2^2 (ball)[/SIZE]

where the losses are referring to the small losses due to deformation of the ball and the clubface during impact. This formulation is erroneous. The clubhead still has an appreciable velocity after impact and the formulation should have been:

[SIZE=-2]½ m1*v1^2 (clubhead) = ½ m1*u1^2 (clubhead) + ½ m2*u2^2 (ball) + losses [/SIZE][/quote]

I appreciate your clarifications to the final formula... you are quite correct.

As to the balance of the discussion, my points were directed to questions that clearly had the role of momentum and kinetic energy confused. I was trying to explain the difference, simply with the point being pretty much what you already said. However, the concept that angular monentum is not conserved because there was none to start with, seems a bit bogus. Angular momentum is generated and "redistributed"(your word) during the downswing. "Redistribution" = conservation, no? The consideration I was trying to explain is the big circle (initial downswing), small circle (release) and how the greater the difference between (later release) them the greater the clubhead speed and associated kinetic energy. The second part of the discussion about kinetic energy was to explain that kinetic energy was the appropriate mechanism for energy(not momentum) transfer to the ball and how maximixing clubhead speed in step 1 resulted in greater ball speeds and greater distances.

If you think about this in very simple terms, if you attempt to influence impact, it will be over before you can do so. Thus, the angular momentum created during the downswing by maximizing lag (the diameter of the small circle) IS about what happens on the way to the ball. How fast the ball flies away is a direct result of maximizing the efficiency of this effort. What happens after the ball is gone is of no consequence to the ball, so Kinetic energy transfer is about what happens AT the ball.

Were I trying to explaing this to someone with a rigorous scientific background such as yours, I would have proceeded differently, but thanks for the clarification

G2M

 

[ThinkingPlus]

Silly Was Misunderstood

Steph, qualifying the concerted efforts of a group of respectable English scientists as silly without even having taken notice of their finding is not a very scientific attitude.


But you don’t have to buy the book by Cochran & Stobbs. All you have to do is to have a look at my post. Why don’t you try to refute my arguments, should be straight forward. I know it has to do primarily with conservation of momentum and you have shown some obvious weakness in this area but I can give you a hand if required.

Or if you feel that approach to be negative and like to be positive why not formulate your theory and calculate with it the significant increase in departure speed of the golf ball due to a force applied by the shaft onto the clubhead during the impact interval. Should be rather straight forward. I am really looking forward to your theory and calculations.

It is very comfortable to remain in the domain of vague philosophical statements but science is more about precision and about things which can be quantified. So give it a try knowing that you are risking becoming a persona non grata on your forum.

The silly comment was not meant in a derogatory fashion (more out of frustration at not having it at my fingertips). It is referenced so much, but very few ever provide any concrete information from the book other than conclusions (I appreciated your direct quote). I have ordered the book. It should make for an interesting read.


I cannot go to your web site here at work. It is blocked. I can look it over when I get home. I also never said the speed increase was significant. That depends upon the acceleration.

 

[Biffer]

ThinkingPlus,

I heartily recommend the C & S book. I believe you will find it is one of the best scientific sources available, concerning the workings of the golf swing.

Biff

 

[mandrin]

some food for thought

---
I also never said the speed increase was significant. That depends upon the acceleration.

'I also never said the speed increase was significant. That depends upon the acceleration.’

I would appreciate it if you would make a clear statement. It starts already to become a bit vague. If considered not significant implies that you agree with me.

‘I also never said the speed increase was significant. That depends upon the acceleration.’

I like to point out that whatever a golfer is doing he strives to have the maximum clubhead velocity close to impact and hence minimum acceleration. If there is any significant acceleration through impact implies that he has wasted some of his efforts.


Steph, do you believe that one can influence impact to any discernable degree? HK states that one can resist clubhead impact deceleration, (2-E). You agree?

If you believe that HK is correct than do you believe also, as a consequence, that one can, in a discernable way, increase the ball departure velocity, by any type of action, used during the impact interval?