Endless belt and release physics

[Jeff]

Bagger

You would have to supply a solid physics/mathematical explanation for your assertion that a skier cannot accelerate between point B and point C if he keeps his skis constantly angled for me to consider your assertion seriously. Those U-tube waterskier competitors straightened their skis after accelerating sufficiently, so that they could have a straight-line directional launch from that launching platform.

There is a big difference between a waterskier between point B and point C (and Tiger Woods' club between point B and point C in his swing). Because of the presence of waterdrag and an increasing angle between the rope and the the skier's curved path, the skier will slow down as he passes point C and approaches the boat. By contrast, in a golf swing, air-resistance doesn't impede the release phenomenon in a golf swing, and there is no reason why the club cannot continue to accelerate between point B and point C. In fact, the club does and the clubhead passes the hands after impact.

The waterskier example obviously has limited analogy to a golf swing because the left hand undergoes a 90 degree rotation during the release swivel, as you pointed out, and that is an obvious confounding variable.

My only point of using the waterskier analogy is to give an analogous, easy-to-understand, example of the principle that underlies the release phenomenon - that it is due to angular acceleration developing because the hand pull on the grip is at an angle to the club's COG-momentum and that i) variations in hand speed and ii) hand arc curvature at all time-points during the downswing will cause variations in the degree of angular acceleration during the downswing, and therefore release variations - between different golfers (as nm golfer's mathematical explanation predicts).

Another added point - I have a PingMan-type driver-testing machine at the golf facility where I practice, and I have studied that machine's release action. It has a passive hinge joint that can rotate >90 degrees to simulate the release swivel. Interestingly, it always rotates perfectly during the release even though the hinge joint is totally passive - I presume that it has something to do with the COG of the clubhead causing the clubhead to automatically rotate to a square alignment at impact. I also have noticed that the central arm's swingarc, and therefore hinge joint's (between the central arm and clubshaft) swingarc is circular, and that the central arm travels at a constant speed. There is no endless belt pulley analogy that is applicable to that machine and yet it releases the clubshaft perfectly/naturally - the only "release phenomenon" explanation that presently makes sense to me is nm golfer's mathematical explanation.

Jeff.

[Bagger Lance]

You would have to supply a solid physics/mathematical explanation for your assertion that a skier cannot accelerate between point B and point C if he keeps his skis constantly angled for me to consider your assertion seriously.

There is a big difference between a waterskier between point B and point C (and Tiger Woods' club between point B and point C in his swing). Because of the presence of waterdrag and an increasing angle between the rope and the the skier's curved path, the skier will slow down as he passes point C and approaches the boat.
Jeff.

The skiier will slow down when he can no longer maintain his ski angle to the boat and since there is upwards of 800lbs of rope tension while accelerating as you near point C, that becomes difficult for anyone to maintain.

As an exercise, think of the ski angle to the rope as fixed during initial acceleration prior to point A at 22.5 degrees (direction of intended travel). When the rope angle to the boat has reached 22.5 degrees to the boat, the skier must then have a 45 degree relationship of the rope to the ski in order to continue accelerating on his original linear 22.5 degree direction of travel. Otherwise the effective angle of his ski to the boat is reduced towards parallel with the boat, with accompanying deceleration towards the boats constant speed. So as the skiers ski travels on an arc with an original ski angle at 22.5 to the boat, the angle of the ski must increase for every degree of increase in the angle of the rope to the boat, otherwise acceleration stops.

So yes, at the end of the day, its all about drag and skier strength. You simply cannot maintain a constant ski angle in relation to the boat in order to accelerate to point C.

The waterskier example obviously has limited analogy to a golf swing because the left hand undergoes a 90 degree rotation during the release swivel, as you pointed out, and that is an obvious confounding variable.
Jeff.

I'm happy to agree with you on that.
I tried to dig up some of the physics on skiing but didn't have any success. I hope my simple geometry make sense.

Another added point - I have a PingMan-type driver-testing machine at the golf facility where I practice, and I have studied that machine's release action. It has a passive hinge joint that can rotate >90 degrees to simulate the release swivel. Interestingly, it always rotates perfectly during the release even though the hinge joint is totally passive - I presume that it has something to do with the COG of the clubhead causing the clubhead to automatically rotate to a square alignment at impact. I also have noticed that the central arm's swingarc, and therefore hinge joint's (between the central arm and clubshaft) swingarc is circular, and that the central arm travels at a constant speed. There is no endless belt pulley analogy that is applicable to that machine and yet it releases the clubshaft perfectly/naturally - the only "release phenomenon" explanation that presently makes sense to me is nm golfer's mathematical explanation.
Jeff.

I think we all agree that the hands travel in an arc around a rotating left shoulder joint. Also that clubs are designed to rotate to "square" with normal centrifugal release motion. I think you may be struggling with the concept of aiming the hands with a linear intent to their aiming point, similar to the endless belt diagram.

Everything in a golf stroke is seen as circular but like the skier analogy, what is not seen is linear intent.
But it is the lines that are our guide-lines to good golf.

[Jeff]

Bagger

Thank you for your explanation of the effect of water drag load on the limits of a waterskier's physical ability to maintain a curved path. That makes the waterskier analogy less useful. Hopefully, other forum members will imagine the waterskier situation as an "imaginary situation" that exists in the absence of any water drag load, so that they can basically try to get a visual picture of nm golfer's mathematical explanation. I wonder if there is a better visual analogy that can better convey the "essential idea" behind his mathematical explanation, which seems to be very sound.

Jeff.

[6bmike]

Bagger

Thank you for your explanation of the effect of water drag load on the limits of a waterskier's physical ability to maintain a curved path. That makes the waterskier analogy less useful. Hopefully, other forum members will imagine the waterskier situation as an "imaginary situation" that exists in the absence of any water drag load, so that they can basically try to get a visual picture of nm golfer's mathematical explanation. I wonder if there is a better visual analogy that can better convey the "essential idea" behind his mathematical explanation, which seems to be very sound.

Jeff.

I would have said Thank You to Baggerfor taking the time to explain instead pissing on him. Maybe on your other forum this is protocol.

[Bagger Lance]

Its cool 6B. Given Jeff's distinguished Medical background and attention to detail, I can appreciate where he is coming from.

I took his response as a compliment and kind of enjoyed re-experiencing my Skiing time anyway.

[Jeff]

6BMike

You wrote-: "would have said Thank You to Baggerfor taking the time to explain instead pissing on him."

Wow! I am flabbergasted at this comment. I did thank Bagger. I wasn't insulting him. I acknowledged his greater knowledge re: the effect of water drag load on a waterskier's skis, and I therefore concluded that I would need to find another visual analogy to better illuminate nmgolfer's mathematical explanation.

Jeff.

[nuke99]

that reminds me in the arm stroke,

there are paw, pick , and a very interesting one Pause...

alot of interesting points..

[6bmike]

6BMike

You wrote-: "would have said Thank You to Baggerfor taking the time to explain instead pissing on him."

Wow! I am flabbergasted at this comment. I did thank Bagger. I wasn't insulting him. I acknowledged his greater knowledge re: the effect of water drag load on a waterskier's skis, and I therefore concluded that I would need to find another visual analogy to better illuminate nmgolfer's mathematical explanation.

Jeff.

I find you being flabbergasted hold to imagine. But nothing personal ol chap. It's just you seem less than affable in many replies. Not many rocket scientists on this site but a whole lot of good golfers that know how the sweet spots moves on plane to achieve impact.