Golf club orbits the body?

[Virtuoso]

So, the moon orbits the earth but not exactly. They are both orbiting around a shared center of rotation which is so close to the earth cg that it only appears that the moon is orbiting the earth. The shared center is closer to the earth cg because the mass of the earth is so much greater than the moon.

Can the same be said of the golf swing? Are the golf club and body actually both orbiting a shared center of rotation that is located bewteen the two...but closer to the body cg because of mass differences. Is this why the golfer's head moves away from the target during the bottom of advanced golf swings?

And, because of the dynamic pulling weight of centrifugal force, does the shared center actually move closer to the club cg at the bottom of the swing? The golf club is 100 times heavier at the botton than it is at the top of the swing (the golf club now weighs approx 2/3 to 1/2 the weight of the golfer).

[media]http://www.youtube.com/watch?v=vUuz7BKO9X4[/media]

 

[natep]

Brian mentioned a discovery from the anti-summit that the pivot center could be located outside of the body.

 

[SteveT]

Ummmm ... I think the moon exerts a gravitational pull on the earth causing tides .... but since the golfer and his club are one system, I don't think there is any "dynamic pulling weight of centrifugal force" to cause any distortion of the human body.

However, the clubhead does momentarily 'disconnect' at the flexing, drooping shaft tip ... so it's free mass may exert a minute gravitational pull on the golfer's mass ... but not enough to sense or worry about ...!!!

 

[Ringer]

It's not the pivot center that is outside the body, but the center of mass. Big difference.

 

[Ringer]

So, the moon orbits the earth but not exactly. They are both orbiting around a shared center of rotation which is so close to the earth cg that it only appears that the moon is orbiting the earth. The shared center is closer to the earth cg because the mass of the earth is so much greater than the moon.

Can the same be said of the golf swing? Are the golf club and body actually both orbiting a shared center of rotation that is located bewteen the two...but closer to the body cg because of mass differences. Is this why the golfer's head moves away from the target during the bottom of advanced golf swings?

And, because of the dynamic pulling weight of centrifugal force, does the shared center actually move closer to the club cg at the bottom of the swing? The golf club is 100 times heavier at the botton than it is at the top of the swing (the golf club now weighs approx 2/3 to 1/2 the weight of the golfer).

[media]http://www.youtube.com/watch?v=vUuz7BKO9X4[/media]

Not exactly. Remember, we actually pull on the club with muscular force. This make "orbiting" calculations non-applicable to the golf swing.

 

[natep]

It's not the pivot center that is outside the body, but the center of mass. Big difference.

You may be correct.

I was just quoting what he wrote in the list of a "dozen things from anti-summit":



NO PARTICULAR ORDER....

1. Aaron Zick's new thoracic spine-reative to the swing plane theory.

2. Aaron Zick's observation on the relatively small movement of the right arm relative to the right shoulder.

3. Paul Wood's assertion that NOBODY angle hinges for any length of time.

4. Zick and Wood's assertion that the top of the D-Plane influence from the clubface is mid-impact interval.

5. Zick, Wood and Neal all agreeing that Pushing and Pulling is not only possible at the same time, but necessarily optimal for maximum distance.

6. Rob Neal's stellar explanations of why the golfer NEEDS TO get light on the left foot on the backswing, to optimize power through sheer and ground forces.

7. Zick, Wood and Neal all agreeing on parametric acceleration as a means of adding additional clubhead speed.

8. Zick, Wood and Neal all agreeing that the "Geometry of the Circle" was not even close to being correct.

9. Neal's explanation of why some pivot slack is needed at the top of the backswing.

10. Wood's explanation of how shaft bowing, and forward flexing effected VSP.

11. Neal showing that REAL PIVOT CENTERS could be outside the body, and the centers being used by some were arbitrary at best.

12. Tumble Torque is as real as rain...Zick, Wood and Neal all agreeing.


...much more to come....
__________________

 

[SteveT]

@ natep re:

"7. Zick, Wood and Neal all agreeing on parametric acceleration as a means of adding additional clubhead speed."


I still don't know what force(s) must be applied within the golfswing to achieve 'parametric acceleration'.

Did that point come up in the 'anti-Summit'? Anybody ???

 

[SteveT]

It's not the pivot center that is outside the body, but the center of mass. Big difference.

Good point ... but if the center of mass is outside the body, the body could be in an unbalanced dynamic state ... and you would fall. Does that happen in the golfswing, and when?!

 

[Virtuoso]

Good point ... but if the center of mass is outside the body, the body could be in an unbalanced dynamic state ... and you would fall. Does that happen in the golfswing, and when?!

Steve, but couldn't you have a little more knee flex, and a little more hip bend and have the body cg be floating in front of the belt buckle and still have good dynamic balance?

 

[Virtuoso]

Not exactly. Remember, we actually pull on the club with muscular force. This make "orbiting" calculations non-applicable to the golf swing.

Hi Ringer, could muscular force, or even a fixed length of joints be substituted for gravity for our purposes?

 

[SteveT]

Steve, but couldn't you have a little more knee flex, and a little more hip bend and have the body cg be floating in front of the belt buckle and still have good dynamic balance?

I suppose you could ... and then there is all that "centrifugal" pull force acting on your arms and club that must be countered. Maybe jackknifing the body is necessary to execute a stable controlled golfswing with the CoM hanging there outside he body .. ya think ??

 

[Ringer]

Good point ... but if the center of mass is outside the body, the body could be in an unbalanced dynamic state ... and you would fall. Does that happen in the golfswing, and when?!

Not really.

We don't stand straight up when swinging a golf club, we bend our knees and bend at the hips. This causes a jagged look in the DTL view. Our center of mass would be somewhere in front of our belt buckle and over our knees. That's outside of the body, but we are perfectly balanced.

 

[Ringer]

Hi Ringer, could muscular force, or even a fixed length of joints be substituted for gravity for our purposes?

No because gravity is constant, muscular force is always in flux when we're in motion.

 

[Virtuoso]

No because gravity is constant, muscular force is always in flux when we're in motion.

OK, but what if i wanted to simulate gravity in a space station so I could walk around in it. Could I just design the station like a big donut and then just spin it? At a certain radius and rpm i could simulate 32 ft/s2 and then i could walk around the inside of the perimeter wall?

That doesn't account for muscular force expanding the radius by opening the left wrist joint but it does account for fixed length of segments and the general interchangeability of gravity and centrifugal force.

So, the underlying question is: are the space station walkers stuck to the wall because of centrifugal force (or their bodies' straight-line inertia if you prefer those symantics)?

 

[SteveT]

Not really.

We don't stand straight up when swinging a golf club, we bend our knees and bend at the hips. This causes a jagged look in the DTL view. Our center of mass would be somewhere in front of our belt buckle and over our knees. That's outside of the body, but we are perfectly balanced.

But what if you add that centrifugal pull-velocity force that requires you to haul back even further to counterbalance with all the thrust ... surely that is a state of unbalance ... like the hammer thrower example ...??!!!

 

[Virtuoso]

But what if you add that centrifugal pull-velocity force that requires you to haul back even further to counterbalance with all the thrust ... surely that is a state of unbalance ... like the hammer thrower example ...??!!!

But surely if you stand up straighter and bring the cg back "inside" the body, and then experience a pulling force, you are more likely to fall over because of the new distribution of your mass and the increased height of the cg?

 

[Ringer]

OK, but what if i wanted to simulate gravity in a space station so I could walk around in it. Could I just design the station like a big donut and then just spin it? At a certain radius and rpm i could simulate 32 ft/s2 and then i could walk around the inside of the perimeter wall?

That doesn't account for muscular force expanding the radius by opening the left wrist joint but it does account for fixed length of segments and the general interchangeability of gravity and centrifugal force.

So, the underlying question is: are the space station walkers stuck to the wall because of centrifugal force (or their bodies' straight-line inertia if you prefer those symantics)?

No. There is a big problem with this idea as well. As long as it's a donut shape, the wall (or floor) will just spin around you and you'll hover above it (assuming 0 gravity). In fact, this is similar to the argument of centrifugal force's existence I purposed. Something actually has to still pull you into the wall (or floor). In the case of the "Gravitron" amusement park ride, gravity is what pulls you to the floor of the Gravitron. The floor wants to continue spinning around because it's pivoting. You aren't part of the gravitron so you get flung out to the wall. But make no mistake, if you were to somehow never touch the floor of the gravitron you would just hover above it while the whole thing just spins around you.

 

[SteveT]

But surely if you stand up straighter and bring the cg back "inside" the body, and then experience a pulling force, you are more likely to fall over because of the new distribution of your mass and the increased height of the cg?

Hmmmm ... looks like you've got me ... unless ... there is no outward pulling centrifugal force to work against, and only an inward pulling centripetal force to apply, and then you can go more erect, recapture your 'floating' CofM (not CofG) while maintaining your 'pivot' .... ya think ...???!!!!!!

 

[SteveT]

No. There is a big problem with this idea as well. As long as it's a donut shape, the wall (or floor) will just spin around you and you'll hover above it (assuming 0 gravity). In fact, this is similar to the argument of centrifugal force's existence I purposed. Something actually has to still pull you into the wall (or floor). In the case of the "Gravitron" amusement park ride, gravity is what pulls you to the floor of the Gravitron. The floor wants to continue spinning around because it's pivoting. You aren't part of the gravitron so you get flung out to the wall. But make no mistake, if you were to somehow never touch the floor of the gravitron you would just hover above it while the whole thing just spins around you.

Well then ... if you laid down on the outer wall of the spinning donut space station you could assume a tangential velocity if your friction was enough to glue you to the wall ... then you could crawl along the wall rather than walk and your intrinsic velocity would provide you with a pseudo-gravity .... ya think ..???

As for the golfswing, the only frictional forces you encounter are those between your shoes and the ground, and those forces are a function of the lateral thrust and your normal weight vector ... I think ...

 

[Virtuoso]

No. There is a big problem with this idea as well. As long as it's a donut shape, the wall (or floor) will just spin around you and you'll hover above it (assuming 0 gravity). In fact, this is similar to the argument of centrifugal force's existence I purposed. Something actually has to still pull you into the wall (or floor). In the case of the "Gravitron" amusement park ride, gravity is what pulls you to the floor of the Gravitron. The floor wants to continue spinning around because it's pivoting. You aren't part of the gravitron so you get flung out to the wall. But make no mistake, if you were to somehow never touch the floor of the gravitron you would just hover above it while the whole thing just spins around you.

Yes, exactly, just as if a bug was hovering next to me as I swung a club, and then he grabbed onto the club as it swung by. And then the bug would experience an acceleration induced by centrifugal force.

Obviously, the space station people are not in the reference frame of the space station when they are hovering....but they are when they touch the floor.