TT Myth Busters

[Der_Echte]

Carl, you asked for it...

 

[Killerspintt]

I agree that COR is determined experimentally. So? I agree that the wood density has a lot to do with COR. That is why I use a cutting board to mount rubbers on before I test them. The cutting board absorbs little if any energy but the mass is MUCH greater than that of the paddle..


So how did you do your tests? I don't see what 1/2gt^2 has to do with anything unless your were dropping the balls on the paddles.



It is good enough if the rest of your testing methods are valid.



OK, now you are saying that there is a lot of variance between different YEOs. So does that explain why different people have different opinions?


The difference is that you are equating density with mass and they are not the same although I agree that if all YEOs are the same shape then those with higher density will have higher mass. Mass is taken into account in the speed after impact formula. Therefore it takes into account the density.



If the density changes the mass changes. That is taken into account by the speed after impact formula.[/QUOTE]

WTF, you are still saying no correlation between weight and COR for a given blade ? I don't know who you are, but maybe you are overestimating yourself in the science field.
Or are you accepting that assuming a constant COR to conclude to your "myth tt buster" about the influence of weight is just wrong ? Its not clear.

 

[UpSideDownCarl]

Carl, you asked for it...

Hahaha. Yes, this is the real quantum of table tennis.

The theories being presented about the acceleration of a man falling from the Brooklyn Bridge and the dwell time of the water on contact, this is the important stuff. And it is obvious there are people here who have been chased by the goon squad and were unable to escape.

But the good news is the winner of the debate gets the prize of jumping off he bridge while that Fred Astaire Ginger Rogers song is played.


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[Pnachtwey]

WTF, you are still saying no correlation between weight and COR for a given blade ? I don't know who you are, but maybe you are overestimating yourself in the science field.
Or are you accepting that assuming a constant COR to conclude to your "myth tt buster" about the influence of weight is just wrong ? Its not clear.

The COR and mass are two different variables in the speed after impact formula.
Where is your proof that mass affects COR? A TT ball will bounce off a Kg plate of steel or Kg plate of glass the same way since neither is going to absorb any energy if the glass and steel plates are thick enough so they don’t flex. The density is much different. Answer that one.

You guys are getting off topic and focusing too much on the terminology stuff and not on the myths themselves.

the simple fact is unless you're a research scientist or a qualified phd in physical aerospace or aeronautical engineering i refuse to take your scientific statements as fact without appropriate proof, methodology sample size and statistics.

After thinking about this statement I think it would be good if everyone was this skeptical and applied their skepticism equally.

 

[Pnachtwey]

Power looping is the dominant game, spin is its name and Tenergy is the equipment. Of course, Tenergy really means tensioned grippy inverted rubber

This was from about 7 hrs ago.
NextLevel still believes in the tension fairy even though he can't explain what holds the rubber in tension.

 

[Pnachtwey]

If the density changes the mass changes. That is taken into account by the speed after impact formula.

WTF, you are still saying no correlation between weight and COR for a given blade ?

Bounce a ball on an 10 lb block of steel and then do it again on a 100 lb block of steel and see if the ball bounces any differently. Well, yes in theory they will bounce differently because of the difference in masses but since the balls mass is so small relative to a 10 lb mass or a 100 lb mass it won't make a difference you can measure.

The COR is the ratio of the velocity_after/velocity_before or the sqrt(kinetic_enegry_before/kinetic_energy_after). Neither the 10 lb block or the 100 lb are going to absorb any significant energy from the collision. Therefore COR isn't dependent on mass.

Drop a ball on a pillow. It won't bounce. Drop a ball on a bigger pillow made of the same stuff. It still wont bounce. Make the pillow infinitely bigger, what do you think will happen? It is similar to all the idiots that say thicker sponges make the rubber faster. Defensive players know this isn't true. Sponges absorb energy. If making a sponge thicker would make the rubber faster ( higher COR ) then why not make the sponge very thick. Do you think you can increase the COR enough to get close to 1? That just can't happen. Why? Because the amount of energy the sponge absorbs is equal to the kinetic energy of the ball before impact. When springing back this energy is divided into the energy required to restore the sponge's original shape and then the rest is returned to the ball. The more mass the of the sponge that is distorted the more energy it will take to restore it back to its original shape and the less for the ball.

The speed after impact formula takes the mass and the COR into account.
https://en.wikipedia.org/wiki/Coefficient_of_restitution

I don't know who you are,

Obviously, but you should find out.
Can reference documents to back myself up. The other detractors only have their popular but wrong myths.

but maybe you are overestimating yourself in the science field.

No! I can post a long list of references. The detractors simply don't like me reminding everybody how wrong they are.

Or are you accepting that assuming a constant COR to conclude to your "myth tt buster" about the influence of weight is just wrong ? Its not clear.

NO! I never said COR was a constant. COR varies by impact speed!
I can think of cases where the COR does vary with difference masses but mostly due to different shapes of the mass not the mass alone.

Put a single piece of newspaper on a table and bounce a ball on it. Cut the piece in half and bounce the ball one half of it again. The mass is halved but the ball will bounce the same. Now take the second half and put it underneath the first half and bounce the ball on it. The mass is now the same as the original mass but the bounce will be less because the paper is twice as thick.

See page 7. The document uses the term Epar for the normal COR. You can see that at higher impact speeds the normal COR drops even when bounced off of marble.
http://www.ittf.com/ittf_science/SSCenter/docs/199408014 - Tiefenbacher - Impact.pdf
It isn't the marble or steel that are changing. It is how much the TT ball dimples on impact. The more the deformation the lower the normal Epar.

I have posted a link to this thread over a dozen times but no one seems to understand it.
Notice that on page 1 Tieffenbacher talks about eliminating current mysticisms.

I am not the one that is full of bull.

 

[UpSideDownCarl]

Are you kidding me? Ma Long will never be good enough to tie Jan Ove Waldner’s shoe laces. HeHe. That oughtta get things started. Asbestos underwear on. Let the flame wars begin.

 

[NextLevel]

This was from about 7 hrs ago.
NextLevel still believes in the tension fairy even though he can't explain what holds the rubber in tension.

In the same way you believe you can loop while killing spin on the ball? Sure. Not all of us are dumb enough to confuse language with knowledge. You are.

 

[Der_Echte]

All that could be totally korrekt. I wouldn't know and do not have the inclination to find out. I really personally believe only so much of it applies to me comprehending this and applying it to my table tennis to make my game better I do KNOW that if I can improve my ability to read the opponent AND be better crouched always AND able to READ the ball... If I do this better I KNOW I would get better than I am already. If I could have better TOUCH I would be better.

What is difficult to explain with formulas is how really good players who master the grip pressure right before and during impact... how they can seem to change the laws of physics doing that... that is a thing of wonder to behold and even when you sometimes successfully do it yourself.

Next Level solved the mystery of Rich Dewitt, a certified double bbaadd-azz Jedi-Master of this, with a short explanation of HOW Rich does it, some trial and error, some pondering, and some courage to fight for points.

Hand pressure can change so much in such an inexplicible way that is near IMPOSSIBLE to see at impact. Your only clues are the sound (if any and IF you can hear in a TT hall), the visible spin, (or lack of it), the flight of the ball, and the kick, or lack of it. That is all you got to go on and masters of firming or loosening hand pressure at will are magicians who win with touch vs opponents who would outgun them otherwise.

 

[UpSideDownCarl]

Here, this has all the answers and formulas:

 

[SchemeSC]

Did Der_Echte just type the word "korrekt"?

 

[UpSideDownCarl]

One thing I will say, the necromancer waking this thread from the long dead has shown how much more entertainment there is on the forum when the troll puts the asbestos underwear on and the physics geek stirs up some strife. PNut is multidimensional and at least 3 characters all rolled into one.

I have missed hearing the phrases COR, tension fairy, stupid, idiots and tangential thrown around ad infinitum as though those things would help his 900 (USATT) level topspin rallying skills improve.

Hahaha.


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[Der_Echte]

Did Der_Echte just type the word "korrekt"?

Yes, purpousely.

Sent from Der_Echte's Center of Political Inkorrektness using Auto Korrekt App

 

[guybr50]

haha loved the topic~!
wish i could add something that isnt here already

 

[UpSideDownCarl]

Did Der_Echte just type the word "korrekt"?

Yeah, of course he did. And his use of the term, in this case is as korrekt as can be. Who could be more korrekt than punchy.


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[Liten]

Personal TT-myth list:

1. When you eat a TT ball, it pass all the internal organs and belly intact. (Haz to be false)
2. When Pnut tell Carl hez stupid, NextLevel levels up in height! Just like when you get that mushroom in SuperMario! (Must be true!)
3. The more chicken and beer Der_Echte eats, the more korrekt hiz spelling becomes. (can you hear the "wrong answer"-buzzer?)
4. I love making lists of bogus therums! (also haz to be true!)

 

[UpSideDownCarl]

I think, to me at least, one of the most interesting things about Punchy PNut's most recent rant is that it reveals something worth understanding. On many levels it reveals a person stuck in the formative emotional stages of a preteen. Me, me, me, me.

Obviously, but you should find out.
Can reference documents to back myself up. The other detractors only have their popular but wrong myths.

No! I can post a long list of references. The detractors simply don't like me reminding everybody how wrong they are.

I have posted a link to this thread over a dozen times but no one seems to understand it.
Notice that on page 1 Tieffenbacher talks about eliminating current mysticisms.

I am not the one that is full of bull.

The wind emanating from that direction is related to a pretty clearly devolved emotional level of someone who obviously has bigger psychological issues going on and is choosing to vent and rant here, rather than dealing with his obvious shortcomings. The least of which is his sub-1000 level topspin rallying skills.

 

[UpSideDownCarl]

And those same qualities make it awfully fun to have the guy around. Who else could be so oblivious to his own level and what his videos actually show as someone like Punchy. I think we should all realize how much entertainment this guy brings to the forum as a result of his hubris, complete lack of self awareness and childlike emotional level.

Who else could say with a straight face that he is the best player at the clubs in China aside from the top players and coaches, while leaving out that he plays at clubs where nobody is over 1300. Only someone like him would go out of his way to find a club like that. And then to brag about it as though he was playing at a real club in China with top players!

In a way, if you think about it, this guys emotional handicap has made me laugh so many times it is pretty much uncountable. It is as good as any comedian I can think of.

 

[UpSideDownCarl]

And just wait for the laugh we all will get when he tries to resurrect one of the high/low throw threads from the grave. Anyone have odds on how soon that will happen? I must say though, it is pretty funny to see him hijack his own thread.

 

[Pnachtwey]

In the same way you believe you can loop while killing spin on the ball?

Again you lie.
It was upsidedowncarl that said that not me. I have always said that I was matching the spin when looping back under spin balls. That way I don't apply any vertical force on the ball that would make it go down into the net. You still don't get Newtons laws of motion do you? Why do I waste my time?

Sure. Not all of us are dumb enough to confuse language with knowledge. You are.

I don't believe in the tension fairy and keep spreading that myth. I can loop back balls with extreme back spin with T25, you can't.