Release – 2

[mandrin]

Golfers, teachers and scientists alike have been commonly viewing centrifugal force, acting through the clubhead, as being the cause for release, i.e., the rapid take over of the club re. to the arms. We have seen previously that this explanation of the release action, as it is commonly given by all those being part of and making up the collective wisdom of golf, to be simply wrong.

However, if it is not centrifugal force what than is causing the club to obtain sufficient angular acceleration to be able to rapidly catch up with the swinging arms in the down swing? Having eliminated the centrifugal force acting through the club head there is only the grip end of the club left as a possible input for force/torque to be exerted on the club. What is it we can do or what can possibly happen at the grip and of the club?

-1- pulling and/or pushing force.
-2- exerting torque by either one or both hands/wrists.
-3- controlling trajectory of grip end.
-4- twisting of club around longitudinal axis

One can also look at the kinetic chain action or perhaps take the view of looking at the power flow through the wrists joints due to the action of the passive joint forces.

Grosso modo, however, we are exerting little wrist torque in a down swing but rather mainly exerting a pulling action via the grip end of the club. Hence to obtain a rapid angular take-over for the club implies that this linear pulling force has to create somehow sufficient angular torque, required to cause the rapid angular take over of club re to arms. One can also ask the question - is a circular type of trajectory perhaps optimum to generate this release torque?

It is important to realize that notwithstanding the many moving parts and numerous muscles acting between grip end and ground, the wrists joints are the only place through which any influence can exerted or action can be transmitted onto the club.

There has been, and still is for some, a rather tenacious believe that somehow one can make through action on the grip end increase the effective mass of the clubhead - or, a variation on this theme, resisting deceleration of the clubhead through impact. This we will not discuss, as we all know on this forum, that this isn’t the case.

The scene is set for some more discussion of the release action. There will be undoubtedly many spontaneous and inspiring reactions and comments. So let’s see what happens.

 

[pecky987]

sorry mandrin, didnt read much of the last release thread, as after reading two pages, i got scared at the physics knowledge needed to comprehend and make sense of the subject

however i feel i should take part in this one

ok, if it is not centrifugal force, then can you list what other forces it could be?

my physics knowledge is sketchy at best, btw so centripetal force? or something else?

as mentioned, this may well have been covered inthe other thread, so i apologise in advance

 

[mandrin]

sorry mandrin, didnt read much of the last release thread, as after reading two pages, i got scared at the physics knowledge needed to comprehend and make sense of the subject

however i feel i should take part in this one

ok, if it is not centrifugal force, then can you list what other forces it could be?

my physics knowledge is sketchy at best, btw so centripetal force? or something else?

as mentioned, this may well have been covered inthe other thread, so i apologise in advance

pecky987

Centripetal force implies a center seeking force. Hence, it does not qualify for any release action. The torque required for release is mainly generated by the linear force exerted by the golfer on the grip end of the club.

 

[pecky987]

what effect does gravity have on the release? if any

i'd have thought that as soon as the clubhead gets on the target side of the hands, there is wrist cock, and as soon as it passes the hands, from the face-on view, then it will start uncocking the wrist and/or 'releasing' the club

 

[Bronco Billy]

F=mg

what effect does gravity have on the release? if any

i'd have thought that as soon as the clubhead gets on the target side of the hands, there is wrist cock, and as soon as it passes the hands, from the face-on view, then it will start uncocking the wrist and/or 'releasing' the club

Gravity is Just another Force...... Gravity is Nuthin Special... Same Old F=ma... It just Happens to exist on this Planet and We have to Deal with It.... If Mandrin's Current Theory has any Validity it will Work With or Without Gravity.... I Happen to Believe Mandrin's Current Musings May be Valid...... Isn't it Nice to Know One Can Still Play Golf in a Weightless Environment......

 

[mandrin]

what effect does gravity have on the release? if any

i'd have thought that as soon as the clubhead gets on the target side of the hands, there is wrist cock, and as soon as it passes the hands, from the face-on view, then it will start uncocking the wrist and/or 'releasing' the club

pecky987,

Gravity is very much part of the dubious playground of feel vs real.

There is David Lee’s Gravity Golf and there is also a Jim Flick promoting the notion that gravity is fueling the golfer’s down swing.

Yet when put into in a mathematical model of the golf swing it shows not to play a significant role.

 

[flapro]

I have posted on the linear force in the past, one area not talked about is the force exerted by the feet.

pecky987

Centripetal force implies a center seeking force. Hence, it does not qualify for any release action. The torque required for release is mainly generated by the linear force exerted by the golfer on the grip end of the club.

 

[mandrin]

So long folks, I am deleting the forum from my bookmarks. Useless and not worth the effort.

I have posted on the linear force in the past, one area not talked about is the force exerted by the feet.

flapro, surprising seeing you still around.
Do not hide your lamp under a bushel basket.
Let us poor mortals partake in your profound wisdom.

 

[flapro]

Mandarin, so glad you finally noticed that I am posting for the past 3 years.
Very perceptive.
I can assure you my lamp has not been hidden under a bushel basket.
Can you handle the truth?

flapro, surprising seeing you still around.
Do not hide your lamp under a bushel basket.
Let us poor mortals partake in your profound wisdom.

 

[Bronco Billy]

The Truth.....

Mandarin, so glad you finally noticed that I am posting for the past 3 years.
Very perceptive.
I can assure you my lamp has not been hidden under a bushel basket.
Can you handle the truth?

You Can't Handle the Truth......

 

[mandrin]

Mandarin, so glad you finally noticed that I am posting for the past 3 years.
Very perceptive.

flapro, three years and yet haven’t noticed it is mandrin not Mandarin.
Very perceptive.

 

[Brian Manzella]

My Vote.

Lots of POSITIVE TORQUE involved.

 

[matt kluck]

negative torque

oxymoron

 

[tobell]

"Centripetal force implies a center seeking force. Hence, it does not qualify for any release action. The torque required for release is mainly generated by the linear force exerted by the golfer on the grip end of the club."

Mandrin,

Are you saying the club does not seek the center....the grip end does not seek the center or axis of rotation?

 

[golfspike]

Lots of POSITIVE TORQUE involved.

from the right

 

[Bronco Billy]

May the Force Be with You.....

"Centripetal force implies a center seeking force. Hence, it does not qualify for any release action. The torque required for release is mainly generated by the linear force exerted by the golfer on the grip end of the club."

Mandrin,

Are you saying the club does not seek the center....the grip end does not seek the center or axis of rotation?

The Grip End Seeks the Magnitude and Direction that You Force it to Seek......

 

[mandrin]

"Centripetal force implies a center seeking force. Hence, it does not qualify for any release action. The torque required for release is mainly generated by the linear force exerted by the golfer on the grip end of the club."

Mandrin,

Are you saying the club does not seek the center....the grip end does not seek the center or axis of rotation?

tobell,

The grip end by itself is not seeking anything in particular and hence therefore also not seeking for any axis of rotation.

Visualize an Iron Byron and assume that one can take two different views:

-1- The rigid inner arm is physically constraining the grip end to remain at a fixed distance from the center.

-2- Ignoring the physical constraint imagine an equivalent varying force acting at the grip constantly restraining the grip end to remain at a constant distance from the center.

Both views are valid and both are used in dynamics. The latter one is taken when one is more specifically interested in the behavior of the constraint forces.

In Newtonian dynamics all constraint forces are, by definition, taken into account whereas with approaches such as Kane’s equations, Hamilton’s equations, Lagrangian dynamics and TMT approach, they are not included in the analysis but can be taken into account if required, simplifying considerably the analysis of complex dynamical systems. A very interesting approach, with regard to constraint forces, has been more recently developed by Firdaus Udwadia and Robert Kalaba.

Hence, the centripetal force is simply the force required to restrain a rotating object to stay in an orbit around a center. Normally this is accomplished using a physical connection with the center, i.e., a rigid arm, a spring, lead arm of golfer, etc.. However one can also fancy small rockets acting on an object constraining it in an orbit around a center without any direct physical connection with the center.

Don’t feel embarrassed not feeling at ease with rotational dynamics. It is indeed rather confusing and not easily grasped simply by our intuition. Don’t feel impressed by some who aggressively use bold letters and capitalization to impress the gallery. There is definitely a reason why after several hundred years concepts such as centrifugal force still are a source for heated debate and much confusion both in golf and elsewhere.

 

[Dariusz J.]

It is important to realize that notwithstanding the many moving parts and numerous muscles acting between grip end and ground, the wrists joints are the only place through which any influence can exerted or action can be transmitted onto the club.

Yes, this is the key to understanding the release. Nunchakoo image

Let's imagine (in one-arm example) that the arm is one wooden piece of a nunchakoo; the wrist is the chain; the hand and the club are the other wooden stick.
Now, my take is this - if the wrist (chain) is totally passive all the motion and the body is turning the nunchakoo will not release at all unless we deliberately stop the movement of the 1st wooden stick (arm). This is, more or less, how a slap-hinge release in a rotary swing can look. No other forces are specially necessary, IMHO.
If the wrist (chain) is somehow active and wants to control the release in time the situation is much more complex. E.g. I cannot imagine release without the wrist (chain) no matter what and how many forces are present. We could only manipulate the speed of the whole element (rotational speed of each point on the nunchakoo will be the same).

Mandrin,

As regards my take on the very answer (for what it is worth) - similar to Brian I think it must be linked to change of inertial torque; since the pre-impact torque is negative the whole system (golfer+club) will tend to level the torque back to neutral and, therefore, forced to create a momentary big positive inertial torque. The most efficient release will happen just in moment of levelling the torque, i.e. when it passes from positive to negative one, since the momentary positive torque will be bigger enough to make the change happen.
Of course, it is obvious that the torque will change again to negative one post impact - I can imagine a sinusoide of inertial torque (oscillation) until the
whole systems finally stops.

Cheers

 

[mandrin]

Yes, this is the key to understanding the release. Nunchakoo image

Let's imagine (in one-arm example) that the arm is one wooden piece of a nunchakoo; the wrist is the chain; the hand and the club are the other wooden stick.
Now, my take is this - if the wrist (chain) is totally passive all the motion and the body is turning the nunchakoo will not release at all unless we deliberately stop the movement of the 1st wooden stick (arm). This is, more or less, how a slap-hinge release in a rotary swing can look. No other forces are specially necessary, IMHO.
If the wrist (chain) is somehow active and wants to control the release in time the situation is much more complex. E.g. I cannot imagine release without the wrist (chain) no matter what and how many forces are present. We could only manipulate the speed of the whole element (rotational speed of each point on the nunchakoo will be the same).

Mandrin,

As regards my take on the very answer (for what it is worth) - similar to Brian I think it must be linked to change of inertial torque; since the pre-impact torque is negative the whole system (golfer+club) will tend to level the torque back to neutral and, therefore, forced to create a momentary big positive inertial torque. The most efficient release will happen just in moment of levelling the torque, i.e. when it passes from positive to negative one, since the momentary positive torque will be bigger enough to make the change happen.
Of course, it is obvious that the torque will change again to negative one post impact - I can imagine a sinusoide of inertial torque (oscillation) until the
whole systems finally stops.

Cheers

Dariusz,

I don’t know quite if I understand your post but it appears to me that a nunchaku releases deviously fast even when applying continuously a steady torque at the inner stick as shown in the figure above. I have modeled equal sticks as I thought is the case for nunchakus and used constant torque at the inner center. Hence no deliberate stopping of inner stick whatsoever.

 

[Dariusz J.]

Mandrin,

I meant that if the velocity of inner stick is constant or accelerating (the distances between red dots (chain) are constant or getting bigger) the outer stick will not release - the angle between sticks will remain constant - because the chain is much looser than a human wrist. Hence, I presume, the inertial torque plays much less important role than in case of a human model.

Cheers