Bubka's Energy transfer

[Tim McMichael]

Also Tim, im curious if you know the distance from Joe's top hand hold to the bottom of the box at its largest bend. Basically, as high as he would have been able to hold while stiff poling. Id like to know how that compares to the other 19'7" jumpers top stiff-pole hand holds like bubkas 4.20 (i believe?).

This is very hard to measure exactly, and I don't think we ever had it done for us. Some of the studies USATF did in the late 80's might have that number, but I don't know how to get ahold of them. What I do know from just looking at video comparisons is that his was by far the shortest effective pole length of anyone to ever come close to jumping that high. The physical dimensions involved also indicate that this must be true. If you are much shorter and gripping much lower than the competition the top hand has to be coser to the box at maximum bend.

BTW I saw the clips of your last PR and am very impressed. Great work and a huge improvement since the meet in Forney.

[powerplant42]

vault3rb0y Posted: Thu Apr 17, 2008 11:18 pm Post subject:

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Ok then powerplant, in what form is the energy converted? Your swing on a flexible pole is stored in the pole in the form of stretching and compressing fiberglass. If your swing is adding energy into the vaulter pole system, what form does it take?

I know that whenever I stiff pole, it always seems that my swing is faster... the swing helps move the pole, but in the case of stiff poling, less energy can be stored for less time in the pole.

[altius]

3po -have you ever seen a wrecking ball used to knock a building down =that will will give you some idea of the energy in a swinging body - but read C5 and see what the stiff pole vaulters like Warmerdam said about the importance of the swing.

[VaultPurple]

Ok i just typed a 4 paragraph thing on how the kenetic energy generated by the swing helps the vaulter accheive maximum velocity into the pit and upwards. Then my computer messed up and erased it all, so heres it in short....

When the vaulter is in the C positon, the line through his top arm is the y-axis, and perpendicular to that is the x-axis.

By examining Bubkas 6.15 jump i came to these conclusions.

His trail leg starts behind the y-axis and he swings around his top hand until it becomes in line with his top arm.

When in line with his top arm all of the velocity from his trail leg is parallel to the x-axis, which is towards the pit and slightly upward (depending on how big the "C" is.

This is kenetic energy that came from the body, in the form of the leg muscle causing the leg to swing, that drove him into the pit.


Once he was in line with his top hand and in line with the y-axis, no longer rotated around his top hand, but rather infront of it and around his bodies center of mass.

This rotation reaches maximum upward velocity when at pie (the point where negative x would be on a x,y graph)

When His swing is at pie Bubka begins to drive his hips upward, causing all of his kenetic energy to go in the upward direction to convert the kenetic energy from the swing, more efficiently into upward velocity.

In conclusion, the enitial part of the swing where he is rotating around his top hand places foward energy into the pit.

Then the second part of the swing where he rotates infront of the pole around his on center of mass, uses the kenetic energy from the swing to drive him verticaly.



This in the same sence would work with a straight pole, because the swing can still add kenetic energy to the vault in the foward and vertical directon... the vaulter just wouldnt have the same push from a straight pole as a glass or carbon pole because there is no spring like forces acting on the vaulter.

[vault3rb0y]

Thats what im saying, a vaulters velocity can effect himself on the pole, but none of it will be transferred into the pole. There is a weak vaulter-pole system. A lot of the energy will be lost through the tension difference in the top hand if you compared a stiff pole to a fiberglass one. But your swing momentum can still be used to carry your hips up the pole pretty quickly. Now just imagine timing up that momentum with the momentum given by a recoiling pole! I think a lot of high school athletes swing on a pole, get to a nice inverted position.... and sit there. They will only get the pop that the pole gives them back. IF you can move your hips the entire time like stiff polers had to, you are getting two different forces added together at just the right time. Thats how Bubka and Dial both pushed as far as they did.

[altius]

All there in Chapters 5 and 7 in BTB2.

[vault3rb0y]

And look i managed to figure it out myself! hehe

[VaultPurple]

see what a base in high school physics can teach you....

[vault3rb0y]

The vault really isnt a hard thing to understand in basic physics terms.... But i get the feeling there is something we are missing here though. To give you an idea, heres one of the last paragraphs in my term paper:

[quote]Think about what exactly converts the acceleration of a swing into the pole? It is the weight of the vaulter him/her self, especially as the point farthest down the “radiusâ€

[Tim McMichael]

Vaulterboy may have put this one to rest as well. When Altius agrees with him I think the argument may be at an end.

[Tim McMichael]

At the risk of sounding condescending - Vaulerboy, you have come a long way in a short amount of time. I am seriously impressed.

Not only that, but you have developed an ability present complex ideas in concise and elegant one or two sentence statements. For instance:

"Right now i feel that the petrov model will be the model to produce 20'+ vaulters, but if you are short and slow you will have a hard time vaulting 18'+ with it, and that the tuck and shoot allows ANYONE to push 50"+ and make ANYONE a 19' vaulter, but not much higher, and that if you can jump at a higher angle with a free take off, you are limiting your capabilities by using a tuck and shoot rather than the petrov model."

That's a tidy bit of writing. And this is coming from an English professor.

[vault3rb0y]

Thanks Tim, you are among a handful of people whose compliments about my vault and knowledge i take with the deepest respect. A lot of what I know and understand today stemmed from that talk we had at Forney. And as for my writing, you should thank my Literature and Composition teacher for always yelling "get to the point!" when he would read my essays!