It's a Real Force, this Centrifugal Thing.

[birly-shirly]

Centrifugal Force Myth

“.....Again, here is another scientist stating that there is an outward force moving in the direction of the arrow shown in figure 3. This is incorrect. There is no centrifugal force pulling in the direction of the arrow. If there were such a force, the club could be released and the club would move in that direction. If you release a club at any time during the downstroke, it will go off at a tangent to the arc of the downstroke curve at the time of the release.....

You raise a similar point as by the infamous professor Jack Kuykendall, the self acclaimed World's Leading Scientific Golf Teacher, several years ago. He belittles many, yet is himself totally of base with his basic arguments.

However it is so simple to state the simple facts. Centripetal/centrifugal forces only and only exist when there is either a pushing or pulling force acting on an object towards a center, either stationary or not. When the club shaft breaks or club released, then, instantaneously, there isn't any force acting anymore on the clubhead and hence simply moves away tangentially. JK also comes to this conclusion but it is however completely illogical to use this fact to than deny subsequently the existence of centrifugal force.

He does not realize that centrifugal/centripetal force, by definition, only exist as long as there is a restraining force present and acting toward a center. When a club is released, immediately, there simply is no force acting anymore on the club, hence also no centrifugal force. Therefore, the motion of the club, after being released, can't be used as an argument either for or against the existence of the centrifugal force. That is simply very silly, but nevertheless a basic error made by too many.

Thanks for the response Mandrin.

Thanks also for equating my question with the "infamous", "totally off base" and "very silly" Jack Kuykendall. I'm sure you didn't mean to cause offence.

I understand your argument as being that centrifugal force is the real, 3rd law pair of the force that pulls the clubhead towards the centre of its arc.

In which case, I'd like to ask whether you think that centrifugal force is better explained either:

(a) as a force that pushes the clubhead out, away from the centre of arc; or
(b) as an equal and opposite force to the 100lb pull of the hands on the clubhead (in your worked example), in other words, a 100lb pull in the opposite direction, pulling the golfer towards the clubhead?

 

[birly-shirly]

No fixed center.

Got it now?

Thanks Brian. I got it a while back, but I'm pretty sure you knew that too.

 

[mandrin]

Thanks for the response Mandrin.

Thanks also for equating my question with the "infamous", "totally off base" and "very silly" Jack Kuykendall. I'm sure you didn't mean to cause offence.

I understand your argument as being that centrifugal force is the real, 3rd law pair of the force that pulls the clubhead towards the centre of its arc.

In which case, I'd like to ask whether you think that centrifugal force is better explained either:

(a) as a force that pushes the clubhead out, away from the centre of arc; or
(b) as an equal and opposite force to the 100lb pull of the hands on the clubhead (in your worked example), in other words, a 100lb pull in the opposite direction, pulling the golfer towards the clubhead?

Option a) is no good and is frequently used as an argument against the existence of centrifugal force.

Often it is indeed assumed that the centrifugal force acts outwards on the club head and than the argument goes as follows - centrifugal force can't hence exist since centrifugal force and centripetal force would cancel each other.

However they don't act on the same object. Newtonian force pairs never ever do. A fundamental fact frequently ignored by many and even overlooked by some scientists.

To simplify matters and to avoid any possible ambiguity we consider the clubhead as a point mass and the shaft to be a massless 'rigid' slender rod. For these conditions one has:

- A centripetal force acting on the clubhead, towards the instantaneous center of rotation.

- A centrifugal force acting along the shaft away from the instantaneous center of rotation.

 

[birly-shirly]

Mandrin - unless I've misunderstood you, that sounds awfully like (b).

The centrifugal force acts along the shaft, away from the instantaneous centre of rotation, and does NOT act on the clubhead, therefore must be pulling the golfer towards the clubhead. Have I missed something?

 

[mandrin]

Mandrin - unless I've misunderstood you, that sounds awfully like (b).

The centrifugal force acts along the shaft, away from the instantaneous centre of rotation, and does NOT act on the clubhead, therefore must be pulling the golfer towards the clubhead. Have I missed something?

birly-shirly.... yes you have. Force is a vector quantity, hence qualified by both magnitude and direction. The centrifugal force vector has, for a substantial part of the down swing, an angle of about 90 deg with the lead arm.

 

[birly-shirly]

birly-shirly.... yes you have. Force is a vector quantity, hence qualified by both magnitude and direction. The centrifugal force vector has, for a substantial part of the down swing, an angle of about 90 deg with the lead arm.

Mandrin - I'm listening, but I don't know if you're telling me very much.

You know that I know that force is a vector, and what that means. And I know that you know that "90 deg with the lead arm" could mean 360 different things unless you specify the plane in which the angle lies.

This is interesting stuff to discuss for its own sake. But presumably you had some purpose in mind in setting this thread up. We both agree that centrifugal force does not act on the clubhead - which is probably the most common misconception that I see in this regard.

I got the impression early in the thread that you were going to post an explanation of what centrifugal force actually does achieve in the swing. I'm all for seeing this thread move in that direction.

 

[birdie_man]

Most people are here for solutions that can benefit their own games or teaching. Or at least the majority does not seem to be into really technical discussions.

Even with how much I am now into instruction I find a lot of it wears me out.

To be honest that could just as easily go for something from Brian like Trackman numbers and measured numerical adjustments (or whatever) or something from yourself.

I presume you understand this to some degree. Perhaps you cannot relate to it as well due to your highly analytical nature and interest in science and physics. Though I of course really do not know.

I guess if something does not capture me at the time (as I casually browse) I mostly just will not pursue it. Certainly some amount of effort can reasonably be expected. But I do not go onto the internet to kill myself "grinding" over learning something. Again that is not necessarily a knock on your work...but reflective of myself and my own tendencies.

Often I will make an extra pointed effort to give certain threads a chance but I usually I gravitate to what interests me naturally, automatically. That used to be pretty well everything but I don't put in as much time as I used to. (even then I only skimmed over highly technical discussion)

But having said all that...

At the same time I like to show people where I'm at...give them some effort...and give credit where it is due, as Brian often says. ("help a brother out", I will say )

You have put in lots of work which is plain to see no matter one's inclinations. You could say this material is golf instruction history. (let's be honest...there is plenty of new ground broken on here)

The fact is that you are quite smart and very adapt at what you do. Not everyone can follow it so easily mandrin. Nor do they share your great passion for science.

Regardless of everything, you did get me thinking whether it was how you intended to or not.

Thanks.

Here is some Neil Young:

[media]http://www.youtube.com/watch?v=VhKzbDSOZPU[/media]



My new favourite song, per-se. (Give The Gift Of Neil)

...

PS- I love your threads on other forums where your are warily repelled like some kind of disease-spreading vermin. I like how you challenge people. And I know you might even like to make em look a little silly "on their own turf." This amuses me. And you seem to be pretty well justified.

At times it is sad but The Goofballs can only keep it under wraps for so long mandrin. One can only repel fairness and truth for so long.

(you knowwwww this)

Keep it up if you can. (maybe you will run out of forums) I usually find myself laughing by myself at my computer. (really)

 

[mandrin]

Most people are here for solutions that can benefit their own games or teaching. Or at least the majority does not seem to be into really technical discussions.

Even with how much I am now into instruction I find a lot of it wears me out.

To be honest that could just as easily go for something from Brian like Trackman numbers and measured numerical adjustments (or whatever) or something from yourself.

I presume you understand this to some degree. Perhaps you cannot relate to it as well due to your highly analytical nature and interest in science and physics. Though I of course really do not know.

I guess if something does not capture me at the time (as I casually browse) I mostly just will not pursue it. Certainly some amount of effort can reasonably be expected. But I do not go onto the internet to kill myself "grinding" over learning something. Again that is not necessarily a knock on your work...but reflective of myself and my own tendencies.

Often I will make an extra pointed effort to give certain threads a chance but I usually I gravitate to what interests me naturally, automatically. That used to be pretty well everything but I don't put in as much time as I used to. (even then I only skimmed over highly technical discussion)

But having said all that...

At the same time I like to show people where I'm at...give them some effort...and give credit where it is due, as Brian often says. ("help a brother out", I will say )

You have put in lots of work which is plain to see no matter one's inclinations. You could say this material is golf instruction history. (let's be honest...there is plenty of new ground broken on here)

The fact is that you are quite smart and very adapt at what you do. Not everyone can follow it so easily mandrin. Nor do they share your great passion for science.

Regardless of everything, you did get me thinking whether it was how you intended to or not.

Thanks.

Here is some Neil Young:

[media]http://www.youtube.com/watch?v=VhKzbDSOZPU[/media]



My new favourite song, per-se. (Give The Gift Of Neil)

...

PS- I love your threads on other forums where your are warily repelled like some kind of disease-spreading vermin. I like how you challenge people. And I know you might even like to make em look a little silly "on their own turf." This amuses me. And you seem to be pretty well justified.

At times it is sad but The Goofballs can only keep it under wraps for so long mandrin. One can only repel fairness and truth for so long.

(you knowwwww this)

Keep it up if you can. (maybe you will run out of forums) I usually find myself laughing by myself at my computer. (really)

birdie_man,

Science does not make you swing the club, twist away does. But the basic structure underlying teaching can be influenced by science.

Sometimes it goes the wrong way with TGM pseudo science, whereas D-plane and kinetic chain are more useful examples of appropriate science.

If it also can make you both think and laugh than it appears to be a winning combination.

 

[Jim Kobylinski]

Last year I tried another TGM forum, but it lasted only for a bare 5 days before they pulled the plug, got banned, no message, no single reason being given. Very cheap approach, showing the typical attitude of unhealthy inbred attitude of sects.

mandrin i honestly don't know what forum you are talking about but the above statement really had me laughing out loud (LOL).

I may not respond much in your threads, i don't respond much these days as at all BUT i do read a lot and enjoy what i can from your threads and responses.

 

[mandrin]

mandrin i honestly don't know what forum you are talking about but the above statement really had me laughing out loud (LOL).

I may not respond much in your threads, i don't respond much these days as at all BUT i do read a lot and enjoy what i can from your threads and responses.

Jim,

iseekgolf.

I am not the only one being thrown out. Indeed, anyone not following the strict TGM party line is not welcome. Even Gerry Hogan, a well known Aussi instructor, invited to post in a special thread set aside for him, had enough of it in a very short time and left. Curious bunch, however fitting in quite well with the many queer exotic animals down under.

 

[SteveT]

mandrin: I hate to revive this centripetal/centrifugal argument so belatedly, but after reading your challenging comments I must ask you this:

Please draw a free body diagram of a rotating mass and identify the centripetal and centrifugal force vectors. Also provide relative magnitudes of both forces.

I can draw the centripetal force vector because it is along the radius from the mass to the center of rotation. I am unable to draw the centrifugal force vector because I am unable to identify it.

I'm sure you can agree that all forces must be 'applied' and just don't spring out of thin air.

Trust you are still active on this fine forum.

 

[greenfree]

Please, anything but that...lol.

 

[billmckinneygolf]

Helical: helix-shaped. Twisting while moving laterally.
From Wikipedia: Screw axis - Wikipedia, the free encyclopedia
No fixed center..but orderly, nonetheless.

 

[islandgolf629]

This whole Centripetal Vs. Centrifugal Force issue would be better explained and understood if "Centrifugal Torque" was used instead of Centrifugal Force. But for that to work, one has to understand torque.


cheers,
jak_bot

 

[SteveT]

This whole Centripetal Vs. Centrifugal Force issue would be better explained and understood if "Centrifugal Torque" was used instead of Centrifugal Force. But for that to work, one has to understand torque.

Can you provide us with your explanation of "Centrifugal Torque"? I think I understand 'torque'. Thank you.

 

[islandgolf629]

Can you provide us with your explanation of "Centrifugal Torque"? I think I understand 'torque'. Thank you.

SteveT,

Check out Jorgensen's The Physics of Golf in the Technical Appendix-Section 9, he talks about centrifugal force and centrifugal torque, pp. 178-179 and 182, respectively.

 

[Ringer]

I think it was asked before, but what are the vectors of centripetal and centrifugal forces?

 

[SteveT]

SteveT,

Check out Jorgensen's The Physics of Golf in the Technical Appendix-Section 9, he talks about centrifugal force and centrifugal torque, pp. 178-179 and 182, respectively.

WHOA !!!! My Physics of Golf is a 1993 edition and stops at Section 8 and page 155 !!!!!

Can you provide us with a brief precis of Chapter 9 ... thanks.

 

[natep]

from the book, page 178 :

Centrifugal Force
But when we ride on a merry-go-round we feel a force, we think,
tending to throw us outward from the center. We look outward to see
whether there is something out there pulling on us, and we find
nothing of the kind. For all the forces we have considered so far there
has been something to produce them. We have seen where the force of
our weight, the force in lifting a tea cup, and the force to pull a wagon
come from. This force arises because we are riding on an accelerating
body, the merry-go-round. Such forces, for which we find no origin in
objects such as ropes or rods and that do not produce accelerations in
the direction of these forces are called by some "pseudo-forces," and
this particular one is called a "centrifugal" force.
You may observe this centrifugal force if you place a golf ball on the
surface just inside the windshield of your automobile and watch it roll
from side to side as you drive around a curve. The ball always rolls to
the outside of the curve and rolls more quickly the tighter the turn.
Actually, the ball does not accelerate, it appears to accelerate since
there is no centripetal force to make it turn in the same path as the car.
Its motion is the result of a lack of a centripetal force rather than the
result of an outwardly directed force being applied to the ball. I once
watched a small boy come running down the aisle in an accelerating
subway car. When the car was no longer accelerating and he could
walk back to where his mother was sitting, he told her, "I didn't do it,
the car made me do it." We would say that the force he felt came
because he was riding in an accelerating car.
According to Newton's second law, the centripetal force on a body
moving in a circle is proportional to the mass (weight) of a body multiplied
by its centripetal acceleration. The centripetal acceleration increases with the radius of the circle on which it moves and with the square of the angular velocity of the motion. The centripetal force and
the centrifugal force are not a third-law pair. The force of the string on
the spool and the force of spool on the string are a third-law pair.

page 182:

Centrifugal Torque
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 out to hit the ball. This torque becomes very large.

 

[SteveT]

Thanks, natep .. where did you find those exerpt on the internet .. or did you type them out longhand ..??!!!

I hate to disagree with the late Dr. Jorgensen, who cannot defend himself now .. but I must.

1. Circular motion required constant acceleration because the rotating mass must always be pulled towards the center rotative axis. His example of the boy walking on the train doesn't distinguish between linear and curvilinear motion.

2. The force of the string on the spool and the force of the spool on the string are NOT a third-law pair .. because the string and the spool are a single united body. The third law defines impulse between two independent bodies .. like the clubhead impacting the ball. The string and spool are connected statically, not dynamically.

3. The centrifugal torque of the golf club held at ninety degree acts centripetally on the wrist joint, and the resultant varying direction forces on the wrist are transmitted to the central pivot point .. the axis of the merry-go-round. Dr. Jorgensen's free body diagramming are incorrect and his conclusions are equally incorrect.

What you are hearing is the difference between pure scientists and engineers. Scientists attempt to relate the pure science to the application, whereas the engineer analyzes the application and then applies the science to explain the final design.

All this scientific mumbo jumbo doesn't really amount to a hill of beans to the struggling golfer trying to create a homemade swing or the golf instructor trying to modify the messy golfswing of the pupil. It's all smoke and mirrors. Go hit balls.