KirkB wrote:Pogo, I appreciate your diligence on this.
I had to search for QED on the Urban Dictionary, and here's what I found:
7. QED
What someone writes when insecure about his abilities as a physicist or mathematician to make themselves feel smarter than they likely are. Typically used by douchebags who think they are doing something amazing by proving a problem from a textbook. Usually follows a terribly formed proof which lacks rigor or reasoning.
"x+y=2. Clearly, z=4, QED."
"You're obviously incorrect, as is seen without proof. QED"
There were other variations to the definition, but I like this one the best! ha! ha!
Actually, I'm willing to give you the benefit of the doubt now that you know what you're talking about. Now I just have to recall my high school physics, and try to digest what this means. Maybe I'll take a look at that vid that Baggett's plugging. That might save me from cracking open the physics book.
Don't mess with B.Sc. of EE. :-)
If I just had as many hours of pole vaulting as math and physics drills, I will be world champion. :-)
Now, my diploma is not even worth the paper it is printed on... but this is another story.
Q.E.D. is "an abbreviation of the Latin phrase 'quod erat demonstrandum' (literally, 'that which was to have been demonstrated')..." (Wikipedia)
I just love Latin phrases, on our pit cover I wrote "Hic Rhodus Hic Salta" - which is Latin for "Here is Rhodes, jump here!"
Very interesting explanation of this phrase can be found here:
http://www.marxists.org/glossary/terms/h/i.htmDon't be scared of the word "marxist" - Agapit, Bubka, Petrov, Markov, Parnov and myself lived in marxist-communist countries and are still alive and well. The following quote actually shows that ancient Greeks were practicing pole vaulting:
The origin of this odd saying, whose currency is largely due to Hegel and Marx, takes a little explaining. It originates from the Latin translation: “Hic Rhodus, hic saltus” (“Here is Rhodes, jump here”), a traditional Latin translation [see, e.g., Erasmus, Adagia III.3.28] of the punchline from Aesop’s fable The Boastful Athlete.
The first mistranslation occurs in the translation from the ancient Greek to Latin. The name of the Greek Island is Ροδος (Rodos), but classical greek only had capital letters. Common Greek, with separate capital and lowercase letters was developed as a result of the conquests of Alexander, in order to make the language easier to learn among non-native speakers (which is when they started using accents in writing, to allow non-native speakers to pronounce words correctly). The quote comes from before Alexander’s time, and the word was ΡΟΔΟΣ (RODOS), hence the confusion, because the Greek word ροδος means “rod”, or in Latin “rodus,” which was used to refer to the long stick that athletes uses for pole-vaulting.
Whichever way the fable is translated, the story is that an athlete boasts that he once performed a stupendous jump, and can produce witnesses: the punchline is the comment of a bystander, who says that there is no need of witnesses, since the athlete can demonstrate the jump here and now.
KirkB wrote:So does the formula prove that a takeoff further back than vertical is inefficient? Petrov as much as says so in Appendix A of BTB2, but why then does Bubka think that getting a bit of airtime on takeoff (i.e. a pre-jump) is good? You can't get this airtime if you're under or vertical, so the only way to get it is to be out a bit. From practical experience, I'm in the camp that thinks being out a bit is good, but I'm willing to try to understand the science behind this, and to listen to other opinions.
Kirk
Formula just shows that ideal take-off point is exactly at the place when toe tip just leave the ground, and at same moment pole is just a hair thick far from touching back of the box. Only in that case there is no loses in vertical speed. If you jump too far from that point, the speed (energy) loses are bigger than potential gains. If take-off is way under, too much energy is going to ground instead to vaulter and pole. Please don't ask me to prove last sentence - I am not ready yet and probably will never be. It is just not so easy as ballistic.
Formula is (almost) perfect for explaining flight of cannon ball but is not perfect for humans because, as powerplant42 said, humans are not perfect. It shows that ideal take-off angle for achieving maximal horizontal and vertical distance is 45 degree. Lot of studies shows that take-off angle should be around 20 degree for pole vaulters. Even for shot put, this angle is around 30 degree.
That does not mean you cannot jump 20ft if you are 1ft under or 1ft out and your take-off angle is 15 or 25 degree, but it is highly possible that you will never jump 21ft. As Agapit like to say the energy efficiency is the key. No passive phases and no unnecessary wasting of energy.
My experience is telling me that there should be a sweet spot where free take-off advantages like full stretching of body and taking better preparation for swing are more beneficial than small losing of vertical speed. This is probably what Bubka means.
