Jack Nicklaus on a Centered Pivot

[Mordan]

If you're going to use a different definition of weight then I'm not surprised you're going to disagree with those who use the commonly accepted version (at least from a scientific or engineering point of view, I've no idea if golf group-think has it's own definition of weight).

It is interesting that those who have been the most strident in their belief that there is a weight shift back are those who don't agree with weight being related only to mass and gravity (even though you've quoted the formula weight = mass x gravity in one of your posts Harmonious).

Maybe everyone can agree that Jack's centre of mass does not shift backwards during the backswing, but that he will be exerting more force on the ground with his back foot than his front foot once he commences his downswing?

Originally Posted by Harmonious

Erik J. Barzeski, The Sand Trap: "If you get 90% of your weight on your front foot just after impact or at impact, the only way for there not to be a weight shift would require you to have 90% of your weight forward at the top of your backswing. Any amount smaller than that is, by definition, a weight shift."

I just can't believe that these folks are all "simpletons", "muppets" or "dummies".

Ah very clever but that's referring to impact where I think everyone is in agreement that there should be a weight shift, weight transfer, shift in the centre of mass or whatever you want to call it.

[Mordan]

Originally Posted by saevel25

He's talking about when you get into an elevator, if your on a scale. If the elevator goes up you will weight more, if the elevator goes down you will weight less.

we are Bidpedal creatures, so we are proportional down our midline. That means our weight on our feet,  is proportional depending on how much we are on one side of that line or another. So if you drawa  line dwon the midline of Jack, and his knee kicks in and doesn't pass that midline, then that weight is acting on his left foot.

But I don't weigh any more when in an elevator going up or down. A scale will only tell me how much I weigh when I'm stationary. You can't just redefine a concept like weight for the purposes of a discussion, at least not unless you want to have 6 pages of posts going around in circles.... oh.

[sean_miller]

Originally Posted by Mordan

But I don't weigh any more when in an elevator going up or down. A scale will only tell me how much I weigh when I'm stationary. You can't just redefine a concept like weight for the purposes of a discussion, at least not unless you want to have 6 pages of posts going around in circles.... oh.

It's a terminology thing. Weights do change based on external factors. That's why many people prefer the term, "mass", which is a constant. It could be a misnomer as well, since NASA is clearly lying to us when they say their astronauts are "weightless" during training sessions in descending airplanes.

[newtogolf]

Bit different scenario here as the planes flight simulatas a vacuum that counters the forces of gravity.  I don't think Jack swung in a vacuum that altered the force of gravity.

To create a weightless environment, the airplane flies in a six-mile long parabolic arc, first climbing, then entering a powered dive. During the arc, the propulsion and steering of the aircraft are controlled such that the drag (air resistance) on the plane is canceled out, leaving the plane to behave as it would if it were free-falling in a vacuum. During this period, the plane's occupants experience about 25 seconds of weightlessness, before experiencing about 25 seconds of 2 g acceleration .

The F in the equation is Force of gravity which doesn't change when you're standing in one location.

Originally Posted by sean_miller

It's a terminology thing. Weights do change based on external factors. That's why many people prefer the term, "mass", which is a constant. It could be a misnomer as well, since NASA is clearly lying to us when they say their astronauts are "weightless" during training sessions in descending airplanes.

[chspeed]

Originally Posted by sean_miller

It's a terminology thing. Weights do change based on external factors. That's why many people prefer the term, "mass", which is a constant. It could be a misnomer as well, since NASA is clearly lying to us when they say their astronauts are "weightless" during training sessions in descending airplanes.

Actually, mass is not a constant.. It's related to energy and speed. As my swing speed approaches the speed of light, my mass actually approaches zero. Meaning I have less mass with which to hit the ball the faster I swing - thus the ball wouldn't go as far. Hmmm, maybe I should slow down my swing.

Sorry - couldn't help it ;)

[sean_miller]

Originally Posted by chspeed

Actually, mass is not a constant.. It's related to energy and speed. As my swing speed approaches the speed of light, my mass actually approaches zero. Meaning I have less mass with which to hit the ball the faster I swing - thus the ball wouldn't go as far. Hmmm, maybe I should slow down my swing.

Sorry - couldn't help it ;)

That's a fine theory.

This is a fine thread too. Some guys arguing that changes in Gravitational Force don't result in a change in weight and other guys arguing that a person who's centre of gravity stays in relatively the same place has anything to with a person who sways off the ball as a result of misinterpreting what a weight shift means. This reminds me of a book I read years ago on rituals performed by primitive cannibals and their connection to the eucharist.

[mchepp]

In watching this discussion I am wondering if using Jack as the model is wise. Jack's career was done using a persimmon driver. The best way to hit the persimmon driver is to hit slightly down on it. Today's equipment is hit best with an ascending blow. Might the weight shift pressures be different if Jack was attempting to hit up on the ball as we should using today's equipment?

I for one think that they would. I think it would look more like a Quiros where even at impact it appears that he does not have much pressure in the left foot.

[BallStriker]

Two things I believe....for better or worse..

1.  If you put scales under each of Jack's feet during the swing, it would read considerably higher on the back foot at the top of the backswing.

2  If you draw a line right down the middle of Jack (from head to ground) at setup and then "split him in two" at the top of his backswing using the same line you drew at setup, the two "seperate" parts of his body would weigh nearly the same.

These concepts are not exclusive of each other (as I think the contributers of this thread seem to be arguing about).

[saevel25]

Quote:

But I don't weigh any more when in an elevator going up or down. A scale will only tell me how much I weigh when I'm stationary. You can't just redefine a concept like weight for the purposes of a discussion, at least not unless you want to have 6 pages of posts going around in circles.... oh.

Sure i can, its called physics. Weight is a measurable thing. If i were on the moon, i would weight less than on earth. Our weight is not static, it fluctuates depending on the gravitational pull. Which is an acceleration. Acceleration is a vector, that is, it has a direction, it works in 3 directions, x,y,z axis. If an elevator produces, lets say 1.2 meters per second squared acceleration in the direction our gravity works, down. Then our total acceleration would be 10 meters per second. When we multiply that by our mass, we get the force acting on us, which is our weight. Weight is the force we feel, with gravity acting on us. Thats why in a roller coaster we feel lighter at the top of a hill, and heavier at the bottom of a hill. You can't fight physics.

With regards to jack, you can't argue that as humans we are bipedal. that means we are proportional in weight down our midline. Though if we do not contact the ground with one foot, then all our weight is on the other leg, but as soon as that other foot touches the ground, it gets a proportion of that weight. That depends on how much our muscles support and how much of the body is across that midline. We can not be 100% on the other foot, unless our foot is off the ground. Jack raises his heel off the ground, but that doesn't mean a significant majority of his weight is on his back foot. I can put majority of my weight on my one foot and lift my heel off the ground. Unless we have him on a scale we can never know what his body is doing. All we can do is believe what he says he feels, which might not be right at all anyways.

[johnthejoiner]

[johnthejoiner]

[johnthejoiner]

[iacas]

Originally Posted by Harmonious

Those on one side of this discussion use your current definition of weight shift as "movement of the CG".  Other folks use the definition of weight shift as "the transfer of weight from the back foot to the front foot during the swing".

Those are virtually the same thing. Weight is not the same thing as pressure.

Originally Posted by Harmonious

And, to be clear, in the OP, Jack was quoted "I don't believe in a lateral shift", which some have incorrectly interpreted as him saying "I don't believe in a weight shift". Does anyone really think that Jack didn't believe in transferring his weight during his swing?

During which part of his swing? Backswing, no. Downswing, yes.

Originally Posted by Harmonious

Erik J. Barzeski, The Sand Trap: "If you get 90% of your weight on your front foot just after impact or at impact, the only way for there not to be a weight shift would require you to have 90% of your weight forward at the top of your backswing. Any amount smaller than that is, by definition, a weight shift."

Yeah, that's talking about the downswing . This thread is talking about the backswing . In no way would any of us agree that Jack was talking about the downswing/follow-through.

Originally Posted by Mordan

Maybe everyone can agree that Jack's centre of mass does not shift backwards during the backswing, but that he will be exerting more force on the ground with his back foot than his front foot once he commences his downswing?

Ah very clever but that's referring to impact where I think everyone is in agreement that there should be a weight shift, weight transfer, shift in the centre of mass or whatever you want to call it.

Yes to both. Except I'd say that Jack, because he's flexing his left knee (and even popping his heel off the ground) and lessening the flex in his right knee will feel more pressure in his right leg, but that his CG won't have actually shifted, transferred, or moved much at all. It's got little to do with "commencing the downswing."

Originally Posted by BallStriker

1.  If you put scales under each of Jack's feet during the swing, it would read considerably higher on the back foot at the top of the backswing.

2  If you draw a line right down the middle of Jack (from head to ground) at setup and then "split him in two" at the top of his backswing using the same line you drew at setup, the two "seperate" parts of his body would weigh nearly the same.

These concepts are not exclusive of each other (as I think the contributers of this thread seem to be arguing about).

Agreed. Except perhaps not "considerably" (depending on your definition).

Originally Posted by johnthejoiner

Exactly. John never actually says anything. He just posts nearly random stuff and then fails to back it up.

[Bananarama]

Originally Posted by chspeed

Actually, mass is not a constant.. It's related to energy and speed. As my swing speed approaches the speed of light, my mass actually approaches zero. Meaning I have less mass with which to hit the ball the faster I swing - thus the ball wouldn't go as far. Hmmm, maybe I should slow down my swing.

Sorry - couldn't help it ;)

I believe the energy of the golf swing = mv^2 so as your club head approaced the speed of light, to a point, it should increase the distance even though the mass decreases.

[Bananarama]

correction, i forgot the constant, its E = 1/2 m v^2.  I wouldnt want the nit picker to be re nit picked...

[michaeljames92]

Golf club/ball collision isn't just as simple as energy transfer. There are more things at play.

[soon_tourpro]

what Jack did and what he felt is often not the same.

Its easy to understand he didnt want a lateral shift due to how his swing motion was done.

http://www.youtube.com/watch?v=mU8CHBZY19k

[iacas]

Originally Posted by soon_tourpro

what Jack did and what he felt is often not the same.

That's true of everyone. Jack Grout grabbing your hair will tend to keep you pretty centered, though.

Terrible camera angle btw, unless Jack played the ball barely inside his back foot with a driver.