[ForkaB]

Tom

You need to re-read your Isaac Newton.  The amount of time that ball touches clubhead is essentially irrelevant to the "issue" of velocity (speed) vs. acceleration (and the latter's essential influence on force (i.e. "power" or "distance").

PS--the same principle applies to other bat and ball games (baseball, tennis, cricket, etc.)
PPS--have you ever wondered why in all these games, maximum power (force) is generated when the ball is at the middle of the positioning of the body?  Well, don't worry, because I didn't either, until I started thinking about in after reading this thread last night!
PPPS--it all has to do with the phenomenon of acceleration.......

PPPPS--let me add another thought, because I honestly think I am onto something interesting.  All other things being equal, which will produce the more powerful shot:

A--a swing which hits the ball at a speed (velocity) of 115MPH, but is travelling at 110MPH one second before impact (i.e. acceleration of 5MPH/second)
B--a swing which hits the ball at 115 MPH, but is travelling at 105MPH one second before impact (i.e. an acceleration of 10MPH/second).

PPPPPS--in thinking this through, I think that it is phsysically impossible to be "decelerating" at impact.  If so, you would never actually arrive at the ball.

PPPPPPS--would love to see if this is interesting or just mince from someone who knows.  TEP,why don't you wake up your old buddy FrankThomas?

[TEPaul]

"The amount of time that ball touches clubhead is essentially irrelevant...."

Rich:

I definitely don't know much about my Isaac Newton, that's for sure but your remark above doesn't make much sense to me. It seems only logical to assume that the only thing that IS RELEVENT is the time the ball touches the clubhead. How can the clubhead have any influence on the performance of the ball when it isn't touching it?

Perhaps this is some abstruse physical law your physics genius wife told you about such as if the clubhead has really bad breath somehow the ball accelerates away from the clubhead on its own faster!

[TEPaul]

Rich:

I really don't pretend to know anything about any of this. I definitely am pretty stupid about anything to do with what Isaac Newtown and such came up with.

But a year or so ago I did have a pretty long conversation with Frank Thomas so I could understand some of this stuff. It was COR and the so-called "spring-like" effect I was trying to get some grip on. I was thinking about it like a kid jumping on a trampoline. Frank said with slightly more "give" of the faces of these new drivers the ball just stays on the face a milisecond longer and that alone imparted more energy to the ball creating more distance.

[ForkaB]

"The amount of time that ball touches clubhead is essentially irrelevant...."

Rich:

I definitely don't know much about my Isaac Newton, that's for sure but your remark above doesn't make much sense to me. It seems only logical to assume that the only thing that IS RELEVENT is the time the ball touches the clubhead. How can the clubhead have any influence on the performance of the ball when it isn't touching it?

Perhaps this is some abstruse physical law your physics genius wife told you about such as if the clubhead has really bad breath somehow the ball accelerates away from the clubhead on its own faster!

So, Tom......

Would your ideal club have a face made of silly putty (maximum time on the ball (stickiness), very high COR--if you could swing hard enough to overcome the stickiness.......), or would it be perfectly solid (COR of 0).........??

Get a grip on yourself, man!

[TEPaul]

Rich:

That last post is precisely why you're such a dunce. Taking things to such a ridiculous assumption or conclusion seems to be your standard modus operandi. Are you trying to say what Thomas claims about the increased distance due to slightly more flexible faces of modern higher COR drivers is garbage?

Just so as not to completely blind-side you, I'm really trying to get you to that point where you're actually going to claim on here that your wife knows more about the effects of these things on golf ball distance than Frank Thomas does!  

[Brent Hutto]

I must respectfully point out that Rich is incorrect in his original post on the matter. Tom has the basic conclusion correct. Most people's common sense does not scale down well to extremely short time periods of a fraction of a thousandth of a second. There are two flaws in Rich's reasoning on this matter which are leading him to a plausible yet incorrect conclusion:

First off, any force being applied by the golfer is done at the grip end of the club. The golfer is separated by a long flexible shaft from the clubhead and the fact of the matter is that the shaft has virtually no stiffness at all when it comes to very short time frames. Once impact between the clubhead and ball takes place, at most the first inche or two of the shaft contributes anything at all to the behavior of the clubhead. Any acceleration being applied by the golfer at that moment will, during that fraction of a thousandth of a second, act on the clubshaft by bending it rather than acting on the clubhead by accelerating it.

However, that fact is moot for question being discussed. Let's stipulate for a moment that the shaft is perfectly stiff (which would not be an ideal shaft in the real world, BTW, but rather is a simplifying assumption to examine the more important effect). Let's further suppose that some golfer is able to cause an acceleration 200 feet per second per second, continuing through and beyond impact. That's just over six times the acceleration of gravity ("six gees") and equal to the average acceleration needed to take the clubhead from stationary to 133mph over a downswing duration of one second. The ball is on the clubface for considerably less than one millisecond, that's 1/1000 of a second. So if we measure clubhead speed at the beginning of impact and it is 133mph and it continues to accelerate at 200 feet per second per second then at the instant when the ball leaves the clubface the clubhead will be travelling at 133.133mph. The point being that no reasonable amount of acceleration applied during impact can make more than a fraction of a percent of a difference in the outcome.

The simplistic formulation "Force equals Mass times Acceleration" does not take the time domain into account. It simply says at any moment in time, a certain mass to which is applied a certain (net) force will experience a certain (net) acceleration. Impact between a golf ball and a clubhead is not an instantaneous collision between two inelastic bodies (the canonical example being two billiard balls). The ball squishes onto the face of the clubhead and then rebounds which means that the force and acceleration is changing over that short interval and are not simple scalar quantities. This is because a ball compressed to any given extent stores energy. So some of the "force" is temporarily diverted into ball compression energy rather than causing acceleration. It is the released a moment later causing rather more acceleration than what would be produced by the force coming from the club at that moment (which is by then less because the club has experienced a net negative acceleration due to the "equal and opposite" end of the force applied to the ball).

The bottom line is that the club/ball interaction is a rather extreme example of an inelastic collision. Beause of that, the time domain is everything. You have to know what's going on at every instant of the ball/club contact interval in order to know what the outcome of that impact is going to be. At the root of the required calculations is indeed our old "F=MA" idea but it has to be averaged  (actually integrated) over that fraction of a thousandth of a second taking into account the squishiness of the ball and, in the case of a club with a not perfectly stiff face, the flexing behavior of the clubface. As it turns out, the maximum ball speed for any given clubhead speed tends to take place when the time it takes the clubface to go through one cycle of flexion and rebound is matched to the time it take the ball to go through once cycle of squish and rebound.

It turns out that in general the flex/rebound cycle of a clubhead is much faster than the squish/rebounde cycle of the ball. So the problem is how to slow down the flexion of the clubface. That is what the designers have gotten good at with large Titanium drivers. Therefore, it is that characteristic time that the USGA is in effect limiting to produce the limitation on coefficient of restitution (COR). That COR is simply a summary number that indicates how fast the ball comes off the clubface relative to the clubhead speed at impact. A perfect COR would be one in which all the energy absorbed by the ball in squishing is returned in the form of ball velocity. The USGA has specified just how close to this perfect condition a driver designer is allowed to come and they've set it at a level just a few percent less than what is theoretically obtainable with the kinds of materials we currently know how to build clubs and balls from.

For anyone who reads this far I apologize for conflating energy and momentum as well as any other less than fully qualified approximations to the truth I may have committed. This is just a stream-of-consciousness infodump of what little understanding I have a club/ball behavior. If you're interested in seeing some of the fundamental experimental work that leads to these conclusions I highly recommend "Search for the Perfect Swing" by Cochran and Stobbs. It's a British book written in the 1960's but it pretty much contains all of the fundamentals except perhaps the characteristic time thing.

[Brent Hutto]

Would your ideal club have a face made of silly putty (maximum time on the ball (stickiness), very high COR--if you could swing hard enough to overcome the stickiness.......), or would it be perfectly solid (COR of 0).........??

Actually, it would seem that one optimum solution for the maximum COR problem is a perfectly stiff clubface and a perfectly inelastic ball. Something like a steel hammerhead hitting a steel ball bearing would generate a lot of ball speed for any given clubhead speed. Hitting wedge shots would be tricky, though.

[JohnV]

Ralph,

Check out:

http://www.ruleshistory.com/rules1920.html

This is the 1920 rules of golf.  If you go down the page, you will find the size specification.  These are the R&A's rules, but I have articles from the New York Times and Washington Post about the floater ball that specifically state that the previous standard ball was the 1.62x1.62 ball.  So even if the USGA didn't go along in 1920, they certainly did before 1930.

I have an article from 1926 from the New York Times about the USGA trying to convince the R&A to go to the floater, but that the R&A wasn't ready.  Obviously they were already trying to move in lock step (although the USGA moved away a few years later).

[Marty Bonnar]

Gentlemen, once again, simply ask Uncle Bill Gates for all your knowledge deficiences...

'For an isolated system, total momentum remains unchanged over time; this is called conservation of momentum. For example, when a tennis(golf) player hits a ball, the momentum of the racquet(club) just before it strikes the ball plus the momentum of the ball at that moment is equal to the momentum of the racquet(club) after it strikes the ball plus the momentum of the struck ball'. (my brackets)
Microsoft® Encarta® Encyclopedia 2002. © 1993-2001 Microsoft Corporation. All rights reserved.

PS Momentum = MassxVelocity (NOT acceleration)

FBD.

[ForkaB]

Brent

Thanks for the explanation.

Of course, I knew all that and was just trying to dumb down my posts so Tom Paul might be able to understand.

Rich

PS--I still think intuitively that "acceleration" is involved and that it relates to the acceleration of the golf swing (and not the force initially applied), but I'm just an old fossil who believes that "F" can be the dependent variable in F=MA (i.e. with a given mass (th eclubhead) the amount of force applied to a ball is dependent on the acceleration of the clubhead at point of impact.  I could, of course, be wrong........

[RJ_Daley]

Just going back to the original statement about Craig Wood's long drive feat.  While you are noting that he had a reputation as one of the tour's longest ball drivers, the article doesn't tell us who else may have been in the contest that particular day.  He may have won with 247, but maybe there were no other top eschlon players in the competition; so we may not be getting a good sampling of comparative length at that point.

As to the rest of it - the physics lesson... what Brent said, yeah, that's the ticket....

[BCrosby]

Brent -

You know more about physics than I, but I think your post on the COR issue is slightly misleading.

The issue is what are the most efficient conditions for transferring the force in the clubhead to the ball? That is, what are the conditions under which the least amount of energy is wasted?

It turns out that the most efficient transfer is one in which the ball is deformed the least at impact. (That instant in which a ball at impact goes out of round and then recovers uses up a ton of energy, apparently.) That is why "harder" balls go farther than "softer" balls. They deform less.

If you were designing drivers, you had a mega buck winner if you could figure out a way to make the club face "give" at impact so as to minimize ball deformation. Club manufacturers have known this for years. But there wasn't much they could do about it using persimmon and steel.

Along came titanium and - presto chango - they could build faces that would "give" at impact (the trampoline effect) thus reducing ball deformation, thus increasing the efficiency of the energy transfer at impact, thus causing the ball to go ungodly distances, thus Merion becomes too short or a US Open, thus the world as we know it comes to an abrupt end.

Or something like that.

You may be saying the same thing. It just makes more sense to me coming at it this way.

Bob  

[Marty Bonnar]

...so will the next big thing be 'Silent' drivers which lose no energy as Sound???

FBD.

[TEPaul]

"I must respectfully point out that Rich is incorrect in his original post on the matter."

Brent:

One of the fundamental truths on GOLFCLUBATLAS.com is when you need to point out that Rich Goodale is incorrect about something there's no need whatsoever to be respectful about it! The best policy is to just walk right up to him and deck him and then as he's lying on the floor writhing is the time to discuss things with him! Believe it or not he actually tends to listen better that way!

[TEPaul]

Brent:

Jeeesus Christ, that post #31 is something else. I'm printing it out and pasteing it to my wall. I feel like I just sat in on a class at MIT. If the professor asked me at the end of the class if that sounded right, I'd have to say; "Whatever you say is OK by me professor!"

[BCrosby]

FBD -

Yes. In fact my wife has perfected the silent hit by missing the ball altogether.

I tried to explain to her the elegant physics of the whiff, but she - unaccountably - failed to appreciate my sense of humor.

Bob

[JakaB]

TEPaul,

Do you think Davis Love III could hit a hickory shafted club futher than Walter Hagen could...What got lost in this argument is Ralph's contention that the modern swing is not responsible for an increase in distance...

[TEPaul]

Hey Rich, do you think Sir Isaac used a regular apple or a sticky candied apple? Too bad you weren't around to tell him there might be a big difference!

[TEPaul]

John B:

That'd all depend on what time of the day you asked Walter to do it. Walter wasn't a great morning person.

[Marty Bonnar]

Hey Brent,
Can you so eloquently explain to us the Physics of the 'Thrown Club' scenario too??? You know, Rotational Velocities, Optimal Launch Angle, etc. The way I'm playing right now, I could do with honing my technique!

 
FBD.

[TEPaul]

JohnV:

Check out the appropriate sections ("USGA activities") of Macdonald's "Scotland's Gift GOLF" and you can track the various opinions and the politics of them on that subject between the USGA and the R&A and others of that time.

[A_Clay_Man]

Boy oh boy! After reading all that physics, I'm thankful this sport isn't about;

Power, or,

How far

Just How many!

[TEPaul]

Martin:

If you're in a slump it's not the time to experiment with club throwing. You might hurt yourself somehow. One of the ironies of golf is if you really want to throw a club properly you need to be in calm frame of mind and quite relaxed. The most important factor is remarkably light grip pressure. The last time I threw a club I was so pissed and obviously so tense with such tight grip pressure the club went in a 180 degree different direction than I intended. This added frustration forced me to attack my caddie and wrestle him to the ground causing him to hit his head and become delerious. This eventually landed me in jail.

Have you heard that ditty about the nail that fell out of the shoe of the King's horse?

[JakaB]

If Iron Byron gains or loses weight will that change the force applied to a ball....I'm thinking that if you add weight closer to the club it might help....Would Charles Howell III hit the ball further if he gained ten pounds of muscle but retained the same swing speed....

[ForkaB]

This is slightly OT, but vis a vis "sound" can somebody tell me what it means when a pro tell you that a driver has "good sonics"?  Does it just mean it sounds good, or is there more to it than that.......?

Thanks

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