D'Encausse on ideal technique

[KirkB]

Alan Launder was a good man. Let him rest in peace!

That's all I have to say about the politics of this.

Re the science, I continue to encourage an open dialogue.

Kirk

[grandevaulter]

And here I still am. Figure out what the necessary information would be and post it. I've told you what it would be, I'm just not going to do it again here and make things easy for you. Why should I? This is the first sign that you would do anything other than take shots at me. It's all here. I've written it. If you care, you'll find it.

If we apply your science to these two world class vaulters (Suhr and Feofanova 9" body height difference) with fractionally different post take offs, you are incorrect. Not taking shots, the proof is in the videos and you can't make it up. Consider this notice of refute to one of your theories. "Post take off quantitative differences and equal results" You've got work to do!

This says that IF all other considerations are equal, this is to say they plant/take off the same, and their speed is equal, their CoM's cannot follow the same path through the vault to equal results. This doesn't even consider the angular disadvantage Dial starts out with at take off concerning the pole angle. This demands that their swing approaches be different and consequently that their technique is different. This is why one can take most of the PB model up until take off. It's actually very good. Near perfect I think. The quantitative differences in the vaulters bodies don't matter there. After take off they do. A lot.

Re the science, I continue to encourage an open dialogue.

[willrieffer]

And here I still am. Figure out what the necessary information would be and post it. I've told you what it would be, I'm just not going to do it again here and make things easy for you. Why should I? This is the first sign that you would do anything other than take shots at me. It's all here. I've written it. If you care, you'll find it.

If we apply your science to these two world class vaulters (Suhr and Feofanova 9" body height difference) with fractionally different post take offs, you are incorrect. Not taking shots, the proof is in the videos and you can't make it up. Consider this notice of refute to one of your theories. "Post take off quantitative differences and equal results" You've got work to do!

This says that IF all other considerations are equal, this is to say they plant/take off the same, and their speed is equal, their CoM's cannot follow the same path through the vault to equal results. This doesn't even consider the angular disadvantage Dial starts out with at take off concerning the pole angle. This demands that their swing approaches be different and consequently that their technique is different. This is why one can take most of the PB model up until take off. It's actually very good. Near perfect I think. The quantitative differences in the vaulters bodies don't matter there. After take off they do. A lot.

Re the science, I continue to encourage an open dialogue.

You haven't shown the CoM path! The only way this also would be a possible refutation would be if you provided the other information, measurements, which you haven't. There is NO PROOF in those videos. The eye does not take measurements! That's how unscientific you are! You use your eye and say its "science"! Heck, you don't even have a theory. Just politics and conjecture. This is so completely ridiculous. As I said, its cargo cult science.

Here, answer this question. It's very simple science theory. IF all things are equal, and these two vaulters have different heights, will they swing at the same rate?

Will

[grandevaulter]

Here, answer this question. It's very simple science theory. IF all things are equal, and these two vaulters have different heights, will they swing at the same rate?

Clarify the difference in "things" and "considerations". But yes they do swing at the same rate on different scales.

This says that IF all other considerations are equal, this is to say they plant/take off the same, and their speed is equal, their CoM's cannot follow the same path through the vault to equal results. This doesn't even consider the angular disadvantage Dial starts out with at take off concerning the pole angle. This demands that their swing approaches be different and consequently that their technique is different. This is why one can take most of the PB model up until take off. It's actually very good. Near perfect I think. The quantitative differences in the vaulters bodies don't matter there. After take off they do. A lot.

This is where any ideal singular pole vault model is interrupted.

[willrieffer]

Here, answer this question. It's very simple science theory. IF all things are equal, and these two vaulters have different heights, will they swing at the same rate?

Clarify the difference in "things" and "considerations". But yes they do swing at the same rate on different scales.

This says that IF all other considerations are equal, this is to say they plant/take off the same, and their speed is equal, their CoM's cannot follow the same path through the vault to equal results. This doesn't even consider the angular disadvantage Dial starts out with at take off concerning the pole angle. This demands that their swing approaches be different and consequently that their technique is different. This is why one can take most of the PB model up until take off. It's actually very good. Near perfect I think. The quantitative differences in the vaulters bodies don't matter there. After take off they do. A lot.

This is where any ideal singular pole vault model is interrupted.

Uh, no.

http://en.wikipedia.org/wiki/Pendulum_%28mathematics%29


Thanks for clearing that up.

Will

P.S. More evidence and a history lesson...

Galileo made another intuitive leap that turns out to be approximately true, but not exactly so: he surmised that the length of the string is only thing that determines the period. The size of the arc? Not important. The mass of the pendulum bob? Also not important. (He was right on that one: it turns out the exact mass of the bob isn’t important, as long as it’s sufficiently heavier than the string. The reason for this, believe it or not, is connected to Einstein’s general theory of relativity and something known as the equivalence principle — I’ll return to that idea later on.) A longer string will take a greater amount of time to complete one swing than a shorter string, which you can see from the second figure: it has to travel a larger distance for the same angle of swing. For those unafraid of the math, the relationship is a square root: if you want to double the period of oscillation, you need a string four times the length; to triple it, you need a string nine times longer, etc.

http://galileospendulum.org/2011/05/24/physics-quanta-the-pendulums-swing/

[grandevaulter]

Clarify the difference in "things" and "considerations". But yes they do swing at the same rate on different scales

We have "things and considerations" Which one do you specially want to use as equal?

You haven't shown the CoM path! The only way this also would be a possible refutation would be if you provided the other information, measurements, which you haven't. There is NO PROOF in those videos. The eye does not take measurements! That's how unscientific you are! You use your eye and say its "science"! Heck, you don't even have a theory.

The burden of proof is incumbent upon the expert making the claim. Use this as a teachable moment, You haven't provided any measurements of any single element of RL , Jenn, Svetlana or Sam. The variables exceed any measurable element.

You claim height difference requires each vaulter implement different technique,, I say "not" based upon visual observation. Science on O' wikipedia cut and paste physics master!

This says that IF all other considerations are equal, this is to say they plant/take off the same, and their speed is equal, their CoM's cannot follow the same path through the vault to equal results. This doesn't even consider the angular disadvantage Dial starts out with at take off concerning the pole angle. This demands that their swing approaches be different and consequently that their technique is different. This is why one can take most of the PB model up until take off. It's actually very good. Near perfect I think. The quantitative differences in the vaulters bodies don't matter there. After take off they do. A lot.

This is where any ideal singular pole vault model is interrupted.

[willrieffer]

The burden of proof is incumbent upon the expert making the claim. Use this as a teachable moment, You haven't provided any measurements of any single element of RL , Jenn, Svetlana or Sam. The variables exceed any measurable element.

You claim height difference requires each vaulter implement different technique,, I say "not" based upon visual observation. Science on O' wikipedia cut and paste physics master!

But I have provided proof. It's a physics mathematical proof provided above in the image illustrating the math and science of pendulums. What you keep proving is that you don't understand the image or how science works. When you understand that image, the math and physics, you will understand that I am logically correct. That's in the relationship of math and science to the real world.

Your eye does not provide science. Your eye neither measures things to scale nor does it use math and logic which are the basis of science. That it doesn't is the reason that science formed and exists! SO you keep saying, "my eye*" and inferring that it is "scientific" when nothing could be further from the truth!


And there is a measurement. Those vaulters height as length of the pendulum and where science has proven that the rate of angular change in a pendulum is governed by its length. And its here we get to my proposal. IF they are swinging at the same rate, it can only be because they are being actively different in doing so. It has to be by science. And since they would have to be doing something different i.e. using movements of the body or say differential activity of the left arm to influence and adjust the swing rate, then they can't be ultimately using the same model to vault. That even if they are coached to some ideal model, they physically and intuitively have to personally adjust to their physical differences. Which would mean there is no universal physical model.

Learn the terms in the pendulum image, what they mean and their relation. That's proven math and physics. Until you do, you're just wasting your time in this argument. TZero is relative to l. Until you understand that, you're going to be just flat out wrong...

Will

* Or, "visible observation"

[IAmTheWalrus]

Ok, I have to chime in here because I'm worried this conversation is going to keep going around in circles, which, while entertaining for a time, is not productive.

A few points:

1) There is so much confirmation bias within the Advanced Technique forum that little will be gained by trying to classify vaulters as "PB vaulters" or "<insert model here>." Everyone has their own things they focus on when watching a vault. One person may see a vaulter takeoff inside and immediately assume that he is not a PB vaulter, another may see someone take off free, but bend his trail leg and likewise assume that he is not a PB vaulter. Gibilisco takes off inside and tucks his legs, but he was coached by Petrov. It all comes down to a concrete definition and intent of the vaulter...etc....suffice to say, you are unlikely to clarify things by classifying vaulters as PB or not PB. More likely, you will introcude arguments tangential to the main topic of the post...which I have already forgotten.

2) Science!!! There have been several instances of people trying to support their claims by invoking the righteous name of science in this forum, however, their scientific arguments are often incomplete or full of fallacies. It is difficult to try to describe the vault with a classical mechanical model, and I applaud anyone who tries (not sarcastic at all, I really do mean that). However as is always the case with mathematical models, one must invariably make assumptions or hold certain values constant. In the case of the vault this is especially dangerous, since so many aspects are indeed variable.

Let's take for instance the case of the straight leg swing vs. the tuck. We all know the anecdote of the figure-skater who tucks her leg in to increase angular velocity. Quite often this is assumed to be the same for the vault, and while the same laws of physics apply (obviously) the situation is different, because angular momentum, angular velocity, and the moment of inertia are all variable. In the case of the figure skater the angular momentum is a constant (save for friction), so when she shortens the radius (changes her moment of inertia) her angular velocity MUST increase. With the vaulter this is not the case, which brings me to my 3rd and hopefully final point.

3) We can't forget about the actions of the vaulter. The vaulter is not freely hanging from the pole like the mass on the pendulum shown above, he has several opportunities to add a torque to the system. What makes the situation more interesting is the vaulters physical limitations. a rudimentary understanding of human physiology and biomechanics will tell you that there are limits to the amount of force that can be produced with a particular movement, limits to the speed at which the movement can be produced, and differences in both of these factors depending on the configuration of the vaulters limbs throughout the movement.

My response to why the straight leg swing may be beneficial is as follows: A vaulter (or some vaulters perhaps) cannot increase their swing speed enough by tucking to overcome the change in the vaulter's moment of inertia, resulting in a net loss in angular kinetic energy.

This is a theory, which I have not tested, but I think it is a good theory, based in the mathematics of classical physics which makes the case for the straight legged swing. My point is not to argue for any technical model, only to illustrate how science can be used to support a differing view.

I hope this alternative perspective can help us to move on in our discussion. I will now return to being an observer of this interesting discussion.

Note: I apologize for use of the gender specific pronouns used in this post. The same principles apply for female vaulters and male figure-skaters

[willrieffer]

Ok, I have to chime in here because I'm worried this conversation is going to keep going around in circles, which, while entertaining for a time, is not productive.

A few points:

1) There is so much confirmation bias within the Advanced Technique forum that little will be gained by trying to classify vaulters as "PB vaulters" or "<insert model here>." Everyone has their own things they focus on when watching a vault. One person may see a vaulter takeoff inside and immediately assume that he is not a PB vaulter, another may see someone take off free, but bend his trail leg and likewise assume that he is not a PB vaulter. Gibilisco takes off inside and tucks his legs, but he was coached by Petrov. It all comes down to a concrete definition and intent of the vaulter...etc....suffice to say, you are unlikely to clarify things by classifying vaulters as PB or not PB. More likely, you will introcude arguments tangential to the main topic of the post...which I have already forgotten.

2) Science!!! There have been several instances of people trying to support their claims by invoking the righteous name of science in this forum, however, their scientific arguments are often incomplete or full of fallacies. It is difficult to try to describe the vault with a classical mechanical model, and I applaud anyone who tries (not sarcastic at all, I really do mean that). However as is always the case with mathematical models, one must invariably make assumptions or hold certain values constant. In the case of the vault this is especially dangerous, since so many aspects are indeed variable.

Let's take for instance the case of the straight leg swing vs. the tuck. We all know the anecdote of the figure-skater who tucks her leg in to increase angular velocity. Quite often this is assumed to be the same for the vault, and while the same laws of physics apply (obviously) the situation is different, because angular momentum, angular velocity, and the moment of inertia are all variable. In the case of the figure skater the angular momentum is a constant (save for friction), so when she shortens the radius (changes her moment of inertia) her angular velocity MUST increase. With the vaulter this is not the case, which brings me to my 3rd and hopefully final point.

3) We can't forget about the actions of the vaulter. The vaulter is not freely hanging from the pole like the mass on the pendulum shown above, he has several opportunities to add a torque to the system. What makes the situation more interesting is the vaulters physical limitations. a rudimentary understanding of human physiology and biomechanics will tell you that there are limits to the amount of force that can be produced with a particular movement, limits to the speed at which the movement can be produced, and differences in both of these factors depending on the configuration of the vaulters limbs throughout the movement.

My response to why the straight leg swing may be beneficial is as follows: A vaulter (or some vaulters perhaps) cannot increase their swing speed enough by tucking to overcome the change in the vaulter's moment of inertia, resulting in a net loss in angular kinetic energy.

This is a theory, which I have not tested, but I think it is a good theory, based in the mathematics of classical physics which makes the case for the straight legged swing. My point is not to argue for any technical model, only to illustrate how science can be used to support a differing view.

I hope this alternative perspective can help us to move on in our discussion. I will now return to being an observer of this interesting discussion.

Note: I apologize for use of the gender specific pronouns used in this post. The same principles apply for female vaulters and male figure-skaters

1) My contention is that post take off because of the great diversity in body shape and ability the ideal form explodes in that diversity.

2) I have at once applied models and also talked quite a bit about their limitations. It is in fact a critique of the established models. We often simplify things. I have called it akin to linearization. One indeed has to know these limitations.

3) This discussion has in some respects turned into one of morphology diversity as regards to any model.

b) This may be true. And its also compounded by the angular relation of the CoM in the gravity field and its angular displacement and the deceleration of the CoM to PE gain. From the simple pendulum model it doesn't look good to have the CoM out displaced from the top hand in the horizontal. You are losing compressive force on the pole AND having gravity slow the swing rate even more. It's a very very complicated problem. RL seems to keep trying to slow the CoMs horizontal displacement from the top hand and when and where he can reorienting back and under it as much as possible. Does it offset any potential loss in angular KE? I don't know. Also, since energy can't really be lost, where does it go? My contention in part is it goes into the pole or can be directed into it. So manipulating the angular KE can effect the pole. And if energy is going into the pole it's going to bend more and have a shorter chord affecting the pole rotation speed. RL's approach is that he "balls up" under the top hand. Anyone that's been on a high bar understands it's easier from a dead position to "ball up" under their grip. It shortens the lever. Again, this doesn't refute your claim in the possible. It's just something to think about.

Much of this is about trying to divine if there are some boundary constraints based on size. One rarely sees long gymnasts based generally on the physics of longer rotating levers. But we have seen both shorter and taller vaulters where they may be able to satisfy the very necessary boundary state to complete the vault in different ways.

Will

Feynman on Science http://www.lhup.edu/~DSIMANEK/cargocul.htm