Another Debate

[birdie_man]

Brian...

There's a debate going on in another forum....

http://www.iseekgolf.com/forums/index.php?showtopic=13925&st=80#entry196597

You're good at these kind of things....cause you're always doing your own thinking, tinkering, etc....you have your own take on most things....so I want to at least hear what you think.

The physics end of things gets dicey (especially for ME....and 99% of anyone else for that matter)....but....

The jist is- that some guys (who actually overall DO like TGM) are arguing certain things....some of the issues that have come up:
-----------------------------------------------------------------
1. "Centrifugal Force is a folly"....(especially in the golf swing).
2. There is no such thing as a "pure Swinger."
3. Everyone Hits through Impact to "keep the shaft stressed"........yes.
4. "How come if you swing a hose with a clubhead attached to it the ball won't go as far?"
5. (something about the hands decellerating prior to Impact....not really sure what this is all about or if it's true)
6. What about the PING man? It's got a free wrist hinge, right? Pure-Swinger, no???
7. Bobby Jones?
8. The Uncock/Roll is from the inertia and weight of the clubhead.
9....Know anything about this "MIT study on TGM" deal Brian?
[EDIT]10. Straight Line Delivery Path...actually possible in reality?
-----------------------------------------------------------------

Lots of claims....and they are educated ones.....but it has all kind of left me stranded a bit.....it doesn't matter to my game at all (at all).....but I'd like to at least get to the bottom of it....or somewhat more.....some of this stuff is fairly complicated.

I'm not sure who I believe....I'm not 100% ruling out what these guys are saying just because it's "against TGM"....but I'm not gonna be swayed from what Homer wrote JUST from 'DIS either....I don't know these guys....and honestly, I don't really have a clue if they're onto anything or not.

...

I think it’s OBVIOUS that Centrif. Force is not powering the entire swing per-se (and/or possibly not even active until the Release).....cause YOU have to spin your body first (Centripugal Force, right?)...thus creating the Centrif. Force...?

...or is there even ANY Centrif. Force (acting on the clubhead only, obviously) in the golf swing?

How about just from say, Release to Follow Through? The Throw-Out Action...?

 

[birdie_man]

SOME POSTS</u>:

Initially, the hitting vs swinging concept seemed to hold water to me also. But, after looking more deeply into it, the idea of a 'true' swinger as described by TGM is fanciful. Don't get me wrong - some golfers do apply more 'hit' than others, but I have never seen one who truely and solely swings the club. If there is such a golfer, I guarentee he would not be able to drive the ball 100 metres.

Firstly, as stated previously, THERE IS NO SUCH THING AS CENTRIFUGAL FORCE. Now, even giving Homer the benefit of the doubt that he was refering to clubhead inertia, this alone cannot power a golf swing. The inertia of the clubhead will not cause the clubhead to accelerate, as it is not a force.

Think of it this way. If a true swinger derives power from this imaginary CF, then it would stand to reason that he would hit the ball just as far with a clubhead attached to a piece of string. Clearly this would not happen. There MUST be pressure applied radially to the clubshaft 1/ to cause the clubhead to accelerate faster than the hands and 2/ to support the club against decelaration at impact.

As stated, some golfers apply more radial pressure (hit) than others, but NONE truely swing the club.

======================================================================

CENTRIFUGAL force is supposed to be an outward pulling force away from the centre of the circle. When you swing a club it feels like it is pulling in an outwards direction. But, this feel is deceiving. There is actually no force that pulls the club away from you in this manner.

CENTRIPETAL force is an inward pulling force. It is a real force and is present in every golf swing. This is a brief explanation. An object in motion moves in a straight line unless there is an external force acting upon it. For an object to move in a circle, there must be a force that pulls it in towards the centre of the circle, otherwise the object would continue in a straight line. This force is Centripetal.

In the golf swing, the rotating arms pull the club towards the centre of the circle. This keeps the clubhead travelling in a circular motion. If the clubhead was to fall off at any point in the swing, then the Centripetal force is removed and the clubhead would continue on a straight line in a tangent to the arc. It would not fly out directly away from the centre of the circle as the myth of centrifugal force would have you believe.

So, Centrifugal force is a myth and not present in the golf swing. Centripetal force is real and is present in every golf swing. Maybe this is what Homer meant when he referred to centrifugal force. The point is that Centripetal Force is present in every swing and there is no Centrifugal force. Therefore the 'swinging vs hitting' concept has no scientific basis.

======================================================================

(on Centrifugal Force/Centripetal Force)

Maybe he did confuse the two but it is a little more than just semantics when it comes to the 'hitting vs swinging' concept. Basically every swing uses both a combination of Centripetal Force and Radial Acceleration. No golfer would hit the ball very far without one or the other.

Therefore the absolutes of hitting and swinging are not realities. Some golfers rely on one more than the other but they are denifately both very present in every full golf swing.

======================================================================

>>>TOOLISH: So you are saying the wrist is uncocked by the weight and inertia of the clubhead? Can't say I agree, but interesting theory. And if you are relying on clubhead inertia to uncock the wrist, then yep, arms will have to slow to allow the club to pass the hands.

So the question becomes, is the wrists uncocking a cause or effect?

How about wrist roll?


>>>MICK: Toolish,

You have hit the nail on the head. This is basically how TGM defines 'swinging'. I agree with you that for this to happen the hands have to slow considerably. Further, it would result in extremely short shots.

To answer your question, the wrists uncocking is cause. No imaginary force will uncock them for you.

Mick

======================================================================

Over the past three years my engineering staff and I have spent a lot of time digging deeper into the subject of what the shaft does and how it does it during the swing. We’ve done this through computer analysis and experimentation based on properly applied principles of engineering and physics, as well as with hit testing and launch monitor analysis with different golfers. Even as I write this section of the book, our work is not fully complete in terms of where we hope to eventually be in our goal to fully predict shaft performance for any golfer. However, we do believe we are at a point where we understand the performance of the shaft in the swing more clearly than it has ever been presented before, particularly from the standpoint of being able to offer far better information to guide the process of fitting the shaft more accurately to each individual golfer.
Let me start by first telling you what the shaft does NOT do in the swing. Many, in fact most, clubmakers and serious golfers think that the shaft “loads” up energy from its initial bending at the start of the downswing and then “unloads” in a buggy whip/spring action to slingshot the ball down the fairway. Most think that the shaft does this in a spring back then spring forward manner and that the right shaft really does increase the velocity of the clubhead when it hits the ball.
I’m here to tell you this is not how the shaft works. But don’t feel bad, I used to think the same thing until we really started to look into the subject. I mean heck, when you make a mind’s eye picture of the bending of the shaft in the swing, it all seems logical that the shaft should work like a slingshot or a catapult. Bend it back and let it spring forward to launch the ball. Like I said, it used to make sense to me too.
OK, now you’re sitting there reading this, thinking that I’ve been telling you how much more confidence you will have in your shaft fitting, and wham, I may have just hammered one of your beliefs in shaft fitting that you thought you were sure about. Don’t worry, I had a little difficulty myself in accepting the truth of how the shaft bends during the swing until I started to open my mind to the real explanation of how the golf swing makes this happen.
The reason you need to know exactly how the shaft bends under the influence of the different movements of the swing is because this is the entire foundation of shaft performance.
To know exactly how the shaft bends under the influence of the different actions in the swing is to be able to know exactly whether and how much the shaft will contribute to the outcome of the shot for any golfer. Without this awareness of what causes the shaft to bend as it truly does, shaft fitting can never be more than an exercise in trial and error. So here goes. (The rest of Chapter 5, along with the entire book, Common Sense Clubfitting, will be available before you receive the next (April) E-Tech Report.)"

Credit to Tom Wishon for the above.

 

[bantamben1]

i think most people already know that about the shaft and he is just showing what homer already knew the cog of the clubhead seaks to be inline with grip end thus the bowing of the shaft at the top of the swing and the forward look at the bottom when the clubhead has turned

 

[c21heel]

That is a very interesting debate! And, a very lively one at that. I have found that a lot of learning can take place with an appropriate amount of healthy friction.

One of the items they are discussing is the endless belt effect, which if I understand correctly means the hands do not accelerate during the backswing or the downswing. The hands simply maintain the same RPMs, so to speak, and the clubhead is accelerating in the process. At least this is what I got from watching Brian's video...I could be wrong.

Has anyone ever measured hand speed and/or acceleration of a professional golf swing to verify this?

 

[sooner]

Maybe the down under boys should tell the NASA rocket scientists that centrifugal force doesn't exist. Try this site http://observe.arc.nasa.gov/nasa/core.shtml.html
click educator's resources and then click centrifugal force.

 

[tongzilla]

quote:Originally posted by sooner

Maybe the down under boys should tell the NASA rocket scientists that centrifugal force doesn't exist. Try this site http://observe.arc.nasa.gov/nasa/core.shtml.html
click educator's resources and then click centrifugal force.

Great find sooner! That is by far the best explanation of centrifugal force I've read.

Here's a direct link that gets you straight to the page:
http://observe.arc.nasa.gov/nasa/space/centrifugal/centrifugal_entry.html

 

[mandrin]

I always find it quite amusing this persistent phenomenon of people believing/posting centrifugal force being a hoax, to be a deception or whatever. One obvious reason for this is that this opinion is oh so readily formed, being only one click away.

Think about it for a second, people seriously stating that yes, as a golfer, you really feel an outward pulling force but, too bad, it really does not exist. Use some common sense - it actually does sound quite weird and yet some get really upset about it if you tell them that they perhaps need to see a doctor. [8)]

There are actually two different notions associated with centrifugal force, causing all this confusion, depending if we are dealing with inertial frames or not. Since we are not playing golf inside a car going through a curve we can completely dispense with non-inertial frames. []

We are all playing golf in a normal inertial reference frame. Newton’s third law says that forces always come in pairs. With rotational motion there are hence also a pair of associated forces generated - a centripetal force and a centrifugal force. [8D]

They both only exist when there is some rotation around a center and are an inertial type force as they are generated when there is motion. Not only the centripetal force, but equally the centrifugal force is fiercely REAL and is not some trickery played on us poor golfers. [}]

This frequent argument used to dispense with the existence of centrifugal force namely that if we cut the cord of whirling mass it does not go outward radially but rather tangentially, has no value. The centrifugal force immediately does stop to exist the moment we cut the cord as for that matter the centripetal force.

It is very queer that this whole matter has become so dogmatic for some. A good example is ‘world’s leading scientist golf instructor’, ‘Prof’ Jack Kuykendall, who treats those believing in centrifugal force as morons. People like JK don’t realize that they contradict and invalidate Newton’s third law doing so. [:0]

So rest assured when in TGM, or elsewhere, there is mention of centrifugal force don’t feel shy to assume and claim that you are feeling a real force. You are not deceiving yourself. I know I am going against mainstream but on this I do side 100% with Homer. [^]

 

[daz]

If I swing a club or a weight on string really fast around myself I certainly have to apply a force (normally through my hands and arms) inwards towards the centre of rotation to keep the object turning in the circle and not flying off at a tangent. A measure of how much force I have to apply to do this is Centripetal Force.

(Centripetal Force is not actually a force it is just a measure of how much force is required to keep an object flying in a circle).

At the same time there is certainly an outward pulling force that is trying to pull my arms out of my shoulder sockets (or get me to straighten my arms at least) this is Centrifugal Force.

Try it and feel it for yourself and you'll know there are 2 opposite pulls happening who cares what they are called.

 

[Burner]

"For every action there is an equal and opposite reaction - Newton, loosely.

The action in this case is the generation of Centripetal Force, a genuine force, and the reaction is the bogus Centrifugal "force" which does not and cannot exist without there firstly being the genuine "force" for it to react to.

Homer knew that there was no Centrifugal "force" but, nevertheless, used the term in its commonly accepted golfing sense for ease of understanding of the masses - who, even in these enlightened times, still fail to come to terms with it being a reaction and not a true force.

 

[mandrin]

quote:Originally posted by Burner

"For every action there is an equal and opposite reaction - Newton, loosely.

The action in this case is the generation of Centripetal Force, a genuine force, and the reaction is the bogus Centrifugal "force" which does not and cannot exist without there firstly being the genuine "force" for it to react to.

Homer knew that there was no Centrifugal "force" but, nevertheless, used the term in its commonly accepted golfing sense for ease of understanding of the masses - who, even in these enlightened times, still fail to come to terms with it being a reaction and not a true force.

Burner, tell me my dear friend, how you come to know exactly what Homer did think about the subject. I am ‘burning’ with desire to be enlightened by your insight into Homer deeper thoughts.

You seem to consider reaction forces to be bogus forces. Could you please do the following simple experiment for me? Punch with your bare fist, with all your might, into the nearest brick wall. [}]

Please tell me if the reaction force, sending you undoubtedly hurriedly to the nearest hospital, was not a true force but simply all bogus. Some seem, even in these enlightened times, fail to come to terms with reality.

 

[mrodock]

I am still trying to figure out if Mandrin's condescending tone is more offensive or his incessant use of the various faces at his disposal.

Matt

 

[mandrin]

Burner’s haughty reference to the poor masses - who, even in these enlightened times, still fail to understand, is definitely arrogant. You likely missed it, just getting too ecxcited.

As in science there is also between posters an interaction resembling Newton’s third law. I am simply trying to defend the poor masses, especially so since Burner himself is off the track.

 

[Jim Kobylinski]

mandrin is playing fine...i enjoy you around here mandrin, honestly i do. You make me think which is a good thing

 

[mandrin]

quote:Originally posted by jim_0068

mandrin is playing fine...i enjoy you around here mandrin, honestly i do. You make me think which is a good thing

Jim, some people react like Pavlov’s dogs. [] They see the name mandrin and think, since it is usually done, that they should throw mud to show their unshakable faith in Homer.

However it is not even noticed that I was actually defending Homer and the poor masses in general. I am all for common sense and against any silly pseudo science from any corner.

 

[vandal]

I actually think these might be the two best posts I've ever read by Mandrin. I can even understand them.

 

[Brian Manzella]

Weather permitting, I am doing a bunch of Video Answers tomorrow, this one included.

 

[Biffer]

quote:Originally posted by mandrin
We are all playing golf in a normal inertial reference frame. Newton’s third law says that forces always come in pairs. With rotational motion there are hence also a pair of associated forces generated - a centripetal force and a centrifugal force.

Nice post mandrin.

In regards to the force pairs. According to Ted Jorgensen in his book "The Physics of Golf", the pair of forces would consist of the shaft exerting a force on the clubhead and the clubhead exerting a force on the shaft.

Also, here is an excerpt from the book that I found interesting.

"Again consider a golfer riding on a merry-go-round. Let him somehow be prevented from being thrown off by the centrifugal force acting on him in the rotating system. Let him extend his arms and a golf club out along a radius from the axis of rotation. He feels no torque on the club because the lever arm of the centrifugal force on the head of the club is of zero length. Next, let him hold the club so that his wrists are cocked at ninety degrees. There is still a centrifugal force in the rotating system on the clubhead out along a radius from the axis. With this wrist cock, the centrifugal force will have a lever arm the length of the club. The golfer riding in the rotating system will feel this torque, and without a matching torque on the club by the golfer, the club will start to move out to a greater radius. The torque on the club is thus a centrifugal torque. In the swing of a golf club, this is the torque that brings the clubhead to the ball. This torque becomes very large."

 

[mrodock]

I'm checking the forecast . . .

 

[mrodock]

Brian,

You may already know this, but 7am to 9am is the ticket. After that it looks really dicey. Assumming you are in Louisville.

Matt

 

[mandrin]

quote:Originally posted by Biffer

Nice post mandrin.

In regards to the force pairs. According to Ted Jorgensen in his book "The Physics of Golf", the pair of forces would consist of the shaft exerting a force on the clubhead and the clubhead exerting a force on the shaft.

Also, here is an excerpt from the book that I found interesting.

"Again consider a golfer riding on a merry-go-round. Let him somehow be prevented from being thrown off by the centrifugal force acting on him in the rotating system. Let him extend his arms and a golf club out along a radius from the axis of rotation. He feels no torque on the club because the lever arm of the centrifugal force on the head of the club is of zero length. Next, let him hold the club so that his wrists are cocked at ninety degrees. There is still a centrifugal force in the rotating system on the clubhead out along a radius from the axis. With this wrist cock, the centrifugal force will have a lever arm the length of the club. The golfer riding in the rotating system will feel this torque, and without a matching torque on the club by the golfer, the club will start to move out to a greater radius. The torque on the club is thus a centrifugal torque. In the swing of a golf club, this is the torque that brings the clubhead to the ball. This torque becomes very large."

Biffer, I like Jorgensen’s imagery, it is very clearly showing the torque developed by the centrifugal force. BTW, Prof Jorgensen is one of very few scientists using real science to discuss golf for the general public.

It should be remembered, contrary to what many websites want you believe, namely that centrifugal force is a fictitious force, that it is actually very much a real force and hence active independent of the reference frame used.

If you really feel the need to invoke non-inertial frames than one has indeed to invoke also a fictitious centrifugal force but golf is played in an inertial frame hence hanging one’s arguments on non-inertial frames is artificial and a waste of time.

Another fact useful to remember is that centrifugal and centripetal forces are only existing when there is some restraint relative to a center of rotation. Eg, cord, friction beween asphalt and tires, wall of spinning drum, etc. No restraint,no centri-forces. Also no motion, no centri-forces.

What so many people get all wrong is simply not understanding Newton’s third law. Imagine ‘cutting’ anywhere through the golfshaft - there are than always present the pair of centri-forces but they are not acting on the same point of application.

The centrifugal force acts on the proximal end of the ‘cut’ and the centripetal force acts on the distal side of the ‘cut’. They are equal in magnitude and opposite but also, as mentioned, don’t operate at the same point of application, hence never cancel each other as some people erroneously seem to think.