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(asl) Weight of racket determine how good smash is ?

Discussion in 'General Forum' started by NaruHodo, May 8, 2013.

  1. NaruHodo

    NaruHodo New Member

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    what i know racket with stiff and head heavy is good for offensive example for smashing...

    my question:

    is weight determine how good the racket for offensive ?
    example
    1st racket weight 78gr with same spec such as stiff and head heavy
    2nd racket weight 86gr with same spec stiff and head heavy too

    let say long racket and balance point is the same.. so which one will perform offensive better ? or weight doesn't matter on this case ?

    Thank you
     
  2. amleto

    amleto Regular Member

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    depends on the person holding the racket.
     
  3. NaruHodo

    NaruHodo New Member

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    -_-" let say he holding the same way... U know... Is not about person that I ask.. I ask about weight of the racket..

    Thankyou btw :)
     
  4. visor

    visor Regular Member

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    all else being equal... yes
     
  5. craigandy

    craigandy Regular Member

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    It's an interesting question their must be an optimum weight for a racket to reach maximum smash force given all other factor equal, not just heavier or lighter produces more power. Of course it is technique/player specific but it would be interesting to see the results, if you got say TBH to go into that "Guinness world record smash set up" again and give him different weighted z slashes ranging in weight from 75g to 110g with 5g increments to see the difference in speeds. I am sure Yonex must have research on this.
     
  6. vixter

    vixter Regular Member

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    If you have the strenght to swing the heavier racket with the same speed, then yeah, the heavier racket will produce more power.
     
  7. visor

    visor Regular Member

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    According to Yonex materials, velocity is more important than mass.

    Yonex uses kinetic energy:
    KE=½mv²

    Rather than momentum:
    P=mv
     
  8. craigandy

    craigandy Regular Member

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    Ok so using the formula - I read(yonex promo statement) that the flash boost can swing 20mph faster than a "conventional" racket, so here is a formula comparison for a flashboost 73g regular and a made up flashboost 85g racket since around 85g would be "conventional". I will invent that we swing at 100mph just for the calculation because the interesting part is the difference which is 20 mph.
    So
    KE=½mv²


    54MPS (120MPH)
    0.073KG
    =109joules

    Versus
    45mps(100mph)
    0.085
    =86joules

    As you can see at these swing speeds lighter is better. With these racket weights I calculated the difference levelled off at 250mph(85g)/270mph(73g) swing speed.
    With a 90g racket it levelled off at 180mph keeping the 20mph difference.

    I don't think anybody swings a racket as fast as this (when heavier overtakes lighter in kinetic energy terms).

    So with my vulgar maths and theory it looks like a racket like the flashboost should give you the biggest smash.
     
  9. NeverWalkAlone

    NeverWalkAlone Regular Member

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    That's interesting. Has anyone tried the flashboost yet? That was the same thing that yonex said about voltric series. They claim voltric series produce 15% harder smash compare to other models. However, it's totally different after i compare it to n90. I found that the heavier n90 gives harder smashes more consistently than voltric 80. Heck, i misses the 2nd gen at700 model even more now.
     
  10. HappySachs

    HappySachs Regular Member

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    For what it's worth my smash seems appreciably faster with lighter rackts. It's obviously a subjective measurement but I do seem to be able to swing a lot quicker when dropping from a 3u to a 4u.
     
  11. Tadashi

    Tadashi Regular Member

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    Research exist in the public domain from non-company experimenters on mass weight, swing weight and "racket power" (speed), just a few years old.

    ... wait a sec I just check it to give you the details... sec
     
  12. Tadashi

    Tadashi Regular Member

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    Research exist in the public domain from (Australian) non-company experimenters on mass weight, swing weight and "racket power" (speed), just a few years old.

    ... wait a sec I just check it to give you the details... sec
    --------------------------------

    So here it is. Okay, but I'm only reporting what the science says. Judge yourself. I'm not responsible for world views on physics, or racket design.

    For theory guys: Simple power laws look greater on paper but didn't turn out to be true in the experiments - you cannot establish a simple mass to swing speed formula, you have learned in school. That's what the professor says!

    For sceptics: Experiments kept mass weight constant and changed the swing weight, then swing the racket and measure the velocity. And kept swing weight constant but varied the mass weight, then swing the racket and measure speed.

    The racket lengths and materials therefore were quite different to get reality work.

    Change swing weight (keep mass weight at 0.320 kg): the lower the swing weight, the faster you can swing - regardless how you swing.

    Caveat: if lower swing weights speed up the swing of the racket, a zero swing weight does not make you smash infinetely fast -- because your arm has a swing weight of its own and in reality all rackets have a "high" swing weight.

    Change in Mass weight (keep swing weight at 0.051 kg*m^2 at the handle's end constant): Counterintuitively for non-experts like me, and for experts like physics professors, too, the changes in mass produced no clear relationship to swing speed, hence "lighter rackets" ran as fast through air as "heavier rackets". For instance, the lightest racket in the experiments swung not the fastest. Power point argument: if you average the speeds across different masses, the speed was found INDEPENDENT from mass! Read it again, it blows my mind.

    Researcher came up with new formulas for maximum speed calculations etcetera ... science stuff.

    Conclusion: for rackets lower than 100-150 grams, greater mass makes greater speed, and smaller weights makes slower speeds; above this threshold, all speeds seem to stay constant even if you have a kilogramm of racket to swing.

    Punchline: If you want to have a faster smash, put a little bit of grams and extra weight on the 12 o'clock position of you racket tip, as long as you stay below ... say 120 grams or so, you will change the entire racket design and physics property .... resulting in faster swings! Of course, mind your tennis arm.
     
  13. amleto

    amleto Regular Member

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    That's a ridiculous summary but I think I've pulled you up on that elsewhere. It's impossible for one to be more valid or correct than the other.

    put it like this, E = p^2/(2m)
     
    #13 amleto, Jun 23, 2013
    Last edited: Jun 23, 2013
  14. Cheung

    Cheung Moderator

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    Heck, I need to stop using my 2U racquets then. :D
     
  15. HappySachs

    HappySachs Regular Member

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    I don't know if you've heard, but you can get rackets made out of carbon graphite now days, steel is no longer the in thing ;).
     
  16. craigandy

    craigandy Regular Member

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    I am not sure if I understand what is trying to be said in this report, one paragraph states lower swing weight(which is a head light racket) you can swing fastest then it says put weight on 12o'clock for faster swing (which would increase swing weight and be slower according to the other paragraph)
    Also it said below 100g is threshold but then it says 120g is faster.
    I don't understand what the message is.:)


    Any chance of a link to the report please?
     
  17. amleto

    amleto Regular Member

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    I agree it's not very clear. I think Tadashi changes his meaning when he's talking about speed - sometimes he's talking about racket speed, sometimes it looks like shuttle speed (it's not obvious).


    The punchline is obviously wrong in part as well since he says adding tape gives a faster smash AND faster swing. However, earlier on he says lower swing weight gives faster swing (correct).
     
  18. craigandy

    craigandy Regular Member

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  19. Tadashi

    Tadashi Regular Member

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    VERY LONG POST - you asked for it though.

    PITCH

    There is a nice PSU webpage asking this: "How is it possible that two bats with the same actual weight feel like they are 8 ounces different when they are swung?"

    That's what people usually feel about the weight .. but it's not about the weight.

    ACT1

    But let's talk about head-heaviness and weight first.

    I find throwing tennis balls simpler to throw than a shuttlecock or a ping pong. Note that tennis balls are heavier!

    When it comes to head heaviness, look at baseball bats. Baseball bats have a certain design, a shape, they are fatter at the end, and thinner at the handle. By design, power goes better into the ball if the bat's end is such and such times bigger than the ball itself. See, a bigger billiard ball kicks a smaller billiard ball much better - same thing with "head heavier" baseball bats.

    You can mimick this for any badminton racket by making heads "heavier". That's what the producers do ... they put in a little bit of metal inside the frame at the 12 o'clock tip so it becomes "head heavy." Typically, they have the label "professional" and the AT800 successors would be it, on their balance-flex matrix look at the top and top-right corners, there you have all the nice rackets for hitting.

    (Of course, not everybody can handle a head heavier racket and baseball bat, because most have weak underarms - it's not the racket, it's the weak underarms that cause problems - see that's why there are tennis elbows, and producers say "for professional/tournament" for a reason.

    The true thing about these high priced rackets is: the harder the string tension, the more muscle training you need to handle them, and the harder you can pull, the better engineering must go into your racket frame to withstand forces - which justifies higher prices.

    It also was found that (better) skill correlates with (higher) ball speed/striking speeds, regardless of what racket, so that better players actually need better engineering.)

    Since this is about weights and not about strings tension (although measured by kilograms/pounds, too), not about skill, I skip the problem with strings and I skip the material stiffness and skill, too. That you, please, ignore.

    ACT2

    Now the original, the first, the prime question of THIS thread was: if you lower the grams or have more grams, what's the effect on ball speed. Right?

    The science experiments (DOI 10.1080/02640410500127876 or [2] in the references) suggest the following: from a certain threshold somewhere between 100 and 200 gram onwards up to relevant 1000 grams for any racket (tennis is about 300+ g), the striking speeds do not differ much on average. Okay, again. Take a light racket of weight 100g, a heavier one of 200g and a heavy 300g racket --- do you see increases in striking speed? Not really. 1000g? Not really. Do you see drops in striking speed? Not really. On average, striking speed doesn't change as you change heaviness within these bounds.

    Why it does not change? Because the experiments kept the moment of inertia constant. The 100g racket has had a similar moment of inertia as the heavier rackets. Hence, the striking speed remained relatively the same. There also was not much about striking skill, because they only hit the racket down like knife-cutting and chopping vegetables, or beheading a chicken. Just down. Not much about skill either. So "all else equal," as visor said.

    But why is a tennis ball better to throw than a ping pong? Because among other things, there seems to be this threshold. Below the threshold, you strike/throw faster as the thing gets heavier (from ping pong to tennis ball), but above the threshold, that's no longer true (100g rackets, 200g, 300g). So I say 100, 120, 150g, there you have the threshold. A tennis ball in hands changes your hand's weight much more than a ping pong and you stay below the threshold!

    The thing is that you don't play 150g badminton rackets, you play 85g. So you could buy a 90g or a good old iron-wood frame - I have one, it weights 110g, but it actually is as easy to strike as the modern rackets, and it would increase strike speed compared to a kids' racket of 65g. How do I know? Well, there are other experiments that show it clearly ... weighted badminton rackets correlate with higher striking speeds (measurable and statistically significant but in practice by a ridiculous small margin).


    However, 100g is heavier than 85g and holding heavier things needs (little) more energy, so you can get tired by that little extra weight, I assume. Unless you train your underarm ... which ... as I said ... well, not many people do that, and that's why people like lighter rackets for they would like to swing faster, but they actually like to play ... longer.


    Still, some rackets of the same weight can feel very different. You see, most rackets you buy have a narrow margin of 80 to 90 grams in weight. By numbers, that's just 10 grams maximum difference ... not much, really not much, it's so narrow you could say that there is no real difference.

    But people feel differences when swung.


    ACT3


    Now about swing weight ... pretty simple: lower swing weight, faster swinging; higher swing weight, slower swinging. All experiments show this. Check the DOI above. You can also check the graphs on the net - it's all round the web, if you look for it, you find it, it's in the public domain. Nothing mysterious, completely old information, almost trivial, no drama there, and nothing to dispute.

    This PSU graph, from a Penn State University page [1], USA, http://www.acs.psu.edu/drussell/bats/images/moi-data.jpg shows exactly what I just said in lavishly long paragraphs. It shows the same results as in DOI 10.1080/02640410500127876, which comes from University of Sydney, and University of Technology, Sydney, Australia. Both confirming what I said here, or put it differently, I only report what was confirmed by them independently around the world. So please, no drama. All information is strikingly trivial, old and conventional.

    What you see -- Left graph, on the up down axis: SPEED. Right graph, on the up-down axis: SPEED. So speed is on the y-axis. Left graph, on the left-right axis: WEIGHT (mass). Right graph, on the left-right axis: SWING WEIGHT (moment of inertia).

    On the left graph, there is no change in speeds, but the data points refer to different weights. Right graph: the speed goes down, as the swing weight goes up. Lower swing weight, faster swinging; higher swing weight, slower swinging. Different masses, same speeds.

    Now I only cite what Mr. Russel from PSU writes: "Before you run out to purchase a new bat with lowest moment-of-inertia you can find in order to increase your bat-swing speed in hopes of hitting balls faster, there is a catch. It is true that lower MOI translates to higher bat-swing speed, and that higher bat-swing speed results in higher batted-ball speed. However, a gain in batted-ball speed only results if you are swinging the same bat faster. Swinging a lower MOI bat faster does not resulting in a faster batted-ball speed. "

    EPILOGUE

    If I remember correctly, someone said that Yonex promotes a new racket that can run 20% faster through air? Well, it's the shuttlecock that needs 20% more speed, not the racket swing alone.

    If you remember ... big billiard ball kicks small billiard ball much better. Then you recognise that swinging is not hitting and the physics of hitting is not swinging alone. So, first you need to swing much better and faster, that means mucles, nerves, innervation and training - not just lowering the swing weight! And then this superbly faster power must translate into ball speed at impact, too, hence the racket design and the string and the stiffness and the material and the impact point on the strings ... lots of stuff going on in hitting.

    So, you cannot simply find a one-to-one causation from A to B. That's just not there. If a salesman tells you so, don't buy.

    REFERENCES

    1. Russell, D. A. Swing Weight: Why moment-of-inertia matters more than weight. (2008). at <http://www.acs.psu.edu/drussell/bats/bat-moi.html>
    2. Cross; Bower: Effects of swing-weight on swing speed and racket power, Journal of Sports Sciences, January 2006; 24(1): 23–30
     
    #19 Tadashi, Jun 24, 2013
    Last edited: Jun 24, 2013
  20. Tadashi

    Tadashi Regular Member

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    Absolutely correct, the earlier thing wasn't very .. say accurate. There are so many different speeds out there I always get confused. There is the racket head speed, which is swinging. There is are multiple other angular speeds at various points of the racket, which is still swinging. Then there are different speeds of the shuttlecock, like the speed at impact, before the impact and the terminal speed after the flight downwards ... there are different speeds ... I apologize.

    However, I honestly remember that is quite correct that adding tape makes a great smash ... for reasons states in the second post, I have to check what happens to swing speed by adding tape/extra weight.
     
    #20 Tadashi, Jun 24, 2013
    Last edited: Jun 24, 2013

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