Bubka's Energy transfer

[agapit]

I read somewhere a while back that bubka was the only athlete at a certain competition

This study was from Seol Olympics by Germans and Egorov was the only other vaulter to increase the energy in the second phase.

[vault3rb0y]

Thanks agapit!

[volteur]

hi Agapit

i was drawn here from the mainfesto pit and was hoping if i could draw upon your expertise.

Basically i am wondering how Bubka and Egorov could increase the kinetic energy after the runup and takeoff are complete? I'm wondering does gravity add to the kinetic energy the vaulter has as they descend from the apex of the takeoff?

cheers

Volteur

[powerplant42]

I guess that would make sense, but how exactly? Anyone know the physics of it?

[vault3rb0y]

The same way gymnasts do it, they use their muscles to create angular momentum. This is a quote from earlier in this post

When you swing with any velocity around your top hand, it creates centripital acceleration (Ac=V^2/R). Then your body weight X that acceleration= the force (F=MA), or extra tension, added onto your top hand and down on the pole. Obviously the farther your body weight (hypothetically keep in mind) from your top hand, the more force you will create. Now the only way to properly add the energy is to set up to add this energy before the pole hits the back of the box. Any trail leg movement backwards AFTER the pole has hit the back of the box is actually releasing tension on the pole, and is then cancelled out again as you swing through. At that point i believe, like you said, you have entered the vaulter-pole system and you cannot add energy because of newtons laws. But what if you put energy into the ground at take off, and set up your swing, BEFORE you enter the vaulter-pole system (free take-off/ pre-jump)? I believe you can add the potential energy you have created off the ground by hitting an inverted C, into the pole with a strong swing.

Imagine you are on a thick bungee cord that will react up and down according to your swing. You swing your trail leg back, and the tension of the bungee is released. This is what happens when a vaulter brings his trail leg back AFTER he/she already enters the vaulter-pole system. The bungee actually contracts a little as you lift your trail leg behind you. Then you swing through, and do a bubka. The bungee expands again as you have added tension to it again. Its the same thing on the vault. Unless you are already in an "inverted C" and prepared to swing before the pole hits the back, you will have a hard time increasing the tension of your swing. Now imagine you are standing on the ground and jump into the air, putting your body into an inverted C, THEN grab the bungee and swing. The bungee is not having to absorb the energy of getting into your inverted C, because you did that before you were in the system.

[master]

I'm wondering does gravity add to the kinetic energy the vaulter has as they descend from the apex of the takeoff?
Volteur

What do you mean "descend from the apex of the takeoff?" Properly done, I don't think a vaulter descends until after the apex of the vault, usually somewhere over the bar.

- master

[volteur]

I was talking from an energetic perspective i guess so whilst you do not physically descend the upward lift momentum is slowed for a period whilst this descending energy counters it. It occurs effectively at the end of the takeoff - right where the rockback initiates as i see it.

cheers

Volteur

[vault3rb0y]

I feel like any going into the apex of the vault is going to hurt your jump. As you swing, yes the pole bends but hopefully you do not start to get straight into the vault, or even worse, down into it. If we are striving to be just like the stiff polers, only with a fiberglass pole, our momentum never stops going up. I see a lot of vaulters that swing into the "pocket", or swing and their momentum completely stops, only to watch the energy in the pole give them their pop. But if you jump UP with a free take off into the vault, you can keep your body moving up throughout the entire jump. When you do this you end up adding the velocity you get from the energy of the pole, along with the upward velocity you have from your take off. Think of how stiff polers were able to push so far over their hand grip. Now think of that energy combined with the energy you put in the pole. Thats what we are trying to do.

[volteur]

Hi vault3rb0y i think that explains it really well. That description of the bungee does show how gravity acts on the body in a really subtle way. That guy also talks strongly about the inverted (reversed?) C position in the same way i see it as well. Who on earth is he?

cheers

Volteur

[volteur]

haha oops it is you!

[vault3rb0y]

Haha no worries. My name is Jason Pelletier and i am a senior in High School in Bryant, Arkansas.

[volteur]

that's a handy PR you have there of a high school student. What sort of heights make the US team for World Juniors?