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#ICYMI: Cosmic Queries: Tennis Special Edition

2017-09-07 | 🔗
Are you ready for a deep dive into hardcore tennis physics? This week, Gary O’Reilly and Chuck Nice welcome back sports physicist John Eric Goff to answer fan-submitted questions about tennis, from the silly to the serious.Don’t miss an episode of Playing with Science. Subscribe to our channels on:Apple Podcasts: https://itunes.apple.com/us/podcast/playing-with-science/id1198280360?mt=2GooglePlay Music: https://play.google.com/music/listen?u=0#/ps/Iimke5bwpoh2nb25swchmw6kzjqSoundCloud: https://soundcloud.com/startalk_playing-with-scienceStitcher: http://www.stitcher.com/podcast/startalk/playing-with-scienceTuneIn: http://www.tunein.com/playingwithscienceNOTE: StarTalk All-Access subscribers can watch/listen to this entire episode commercial-free. Find out more at https://www.startalkradio.net/startalk-all-access/

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This is an unofficial transcript meant for reference. Accuracy is not guaranteed.
Skip. The commercials support star talk on patriarch to listen to every episode, commercial, free. I am the other ass types of your personal astrophysicist. The startup network is pleased to present to you, a U show where the universe and sports, and now I am so nice I am going away and we are the whole stop playing with science ready for it. Today is a where we opened the floor was thoughtful playing science family in question, so
if wondered, why your balls and why you must always keep fuzzy do you like I will now you know I can't I'm just gonna go with it, I'm not gonna. Do it I'm just gonna continue and if you have any interest in a new span on a never ending string theory you are in I place because our good friend, Professor ere, it got from Lynchburg College Virginia and author of gold medal physics is the man? I'm locked the answers to your questions. Now, let's get back to some fuzzy balls that spin list ten seconds. I knew you could be this red men like you, a good to have you back. Having been sir I'm doing greatest to be bad, carry agrarian, John! We I valueless. Yes, as you say, what are you up to well are Let us begin in a week, so I've got about three more days before I need to start preparing for them, and it's good to see you
Those kids are getting a quality education, as you last minute, they're curriculum professor. Get it all the research done before the class start at the hour. I, let's get up those crises mark mail from Halifax Nova Scotia on patron. This is how you pose a question to get it on playing with love Vous, show says So I repeat that the funds from the felt cover of a tennis ball helps control its speed and bounce. Would the fuss itself have an effect on the effects of spin? We see more amazing curved shot, so professor, I'm gonna knock that over the net. It's all yours, so with a fuss actually increases the cross sectional area, the ball going through the air, so you get a little bit more area than if it didn't have fast. You get a little bit more air drag on it, so it will slow all down a little bit, I asked for
Span the firs actually does help with the spin but mostly for low span balls. I, when you start getting up to high speeds and high spin, the first ten too late, out on the ball surface a little bit more and you don't notice a quite as much when you get really high spends in a really high speeds. So let's say you take the firs offer the ball. How much would it changed the game? well you're gonna notice that more for the low span, low speed shots, you're gonna get it little bit less of a curve, you're also gonna get a little bit less of an ever bounce off the ground. If you have the funds on there, because you get a little bit more friction, less of about with with what we have a scotch, and if you take the firs off you're gonna reduce the error, drag elevates, the balls are gonna, be moving a little bit faster gather. This touch
on a question from James Arnold from Facebook is wise. Tennis, baby, fuzz, fuzzy bouncy both which you already addressed, is the first important yet with touched on that one, or could it be shaved down chuck? I thought you'd be all over. This cause but I've seen your ball park as it were, and I am seriously I first of all. I am not about to shaping the funds from the balls, because the way I feel as though its it gives the boss a juvenile look, and I for one like mature, looking balls. What that does at an extra wrinkle to the problem doesn't certainly encourage him. Professor, please, we go a long way to go in this showed what's this of confession, of of drought, again, all the rest of it that this first Venus brings to a terrible way when you put as on a tennis ball, what it's actually doing is Kenneth Thicket. The boundary layer of air that surround the ball and
oh, the around the ball, looks a little bit more. What we call lameter than it does turbulent in Attica yeah. Can you explain those two things amiss that suffer low speed? it's the air separates behind the ball kind of it, a big wake. When go a lot faster. The year gets wrapped around the ball or a bit tighter and the so called drag coefficient drops. That was the drag, ISIS we ve talked about on an earlier show. Yeah, you stop it again, professor, so that the fund actually involve. Will thickened that boundary layer and move that dragged crisis too. Higher speed, so you actually get a little bit more the drag coefficient look at more areas of theirs. There's actually considerably more drag on the ball with the fuzz and if you didn't have any other on their. So it's just kind of the opposite of like a boat in a lake dividing the Pope goes, the the bigger the wake is so you're saying the faster this pass bands and goes to the air with the fuss. These
smaller the weak behind it. Well, what with the fund, you actually get a bigger way? We would you say when you, when you cross, that dragged crisis ended turbulent regime. The the wake would actually cut a rap more around the back of the boat and develop a narrower wake. That's what's interesting! Is we ve seen this type of ten spoonful? I can't remember and you just wondering the people who introduced this type of tennis ball into the sport deeds, They would have been all over the physics of it and thinking right. This is how we progress the game. I don't know the actual history Amanda with golf balls. They they started with smooth balls and then the aristocracy notice that when the bourgeoisie were playing with the used balls, did they discarding we're going farther. So now we dimple
balls, I imagine there was some trial and error involved amazement. If you remove the firs, I mean how fast do you want the game too? I mean how how few hits. Do you need a volley for it to be good tennis fast to serve. Would you have on a completely clean that's funny, because thirty, three comfort from Instagram so asked this question how fast the bar have to spend for thus spin to affect the trajectory. So at what point does the bar have to speed up so that the spin can create a different or create movement well, so the mean any type of spanish gonna, give it a little bit of a sideways. Maybe you're always going to have a little bit of this Magnus Forest for even small spin.
The typical angular speed you see on a tennis, ball tend to be somewhere between about sixteen revolutions per second and eighty revelations per second, if you like thinking about Europeans that somewhere between two thousand and five thousand revolutions per minute, Wowzer bad. When there we, when you're thing is sir well in excess of a hundred and twenty miles an hour with a lot of top spin. I mean these things are really spinning and with the speed and actually does the top span for a serve it'll income. Is the available range to something like two and a slash to four degrees, and that gives the play? a little bit more room for error when your aiming fur like this, sideline, are the sorry, the centre, liner, the bat corner for a serve another nice thing about the spanish that when it hits the ground the ball, is spinning, in fact, it show you I would, but when the ball is turning in, it hits the ground the ground in parts a significant amount of food
she nodded and it could actually kick the sped up again. Double the spin you get a lot more spin off the bells and neck and play havoc with some unexpected. Players are slowly now. Can you just a mean because now that you ve open this up, I really just ask for myself: can you explain because that seems counter intuitive the fact that the ball hits the ground? You would think that that would slow the spin down that, in fact, to use the term action? Normally, whenever we think of friction, we think of something being slow down into wretch rose in the retro. So how exactly does it kick the spin up, interesting I'll, try to imagine a ball coming into a surface at an angle, and it has no span when it hits the surface the ball in the surface are gonna rub against each other, and you're gonna have a frictional force in the opposite direction. The way the balls moving
ball actually leave the surface with span, and you to do this with a. If you ever have a super ball, just take it and spin it and drop it straight down in your watch. It gonna walk. You don't look like its walking back and forth with each new balance as the spin changes direction. You write you sound. So that's great, ok, so we ve got a lot. How I told him he's right. Like he's not a professor of physics, you know I'm just showing more resilient agreement. Make hey. You know what you're right like I approve so convention. A doll served comes in the sort of pace. We're talking now a hundred miles an hour plus bought because he in part so much top spent it dives once it clears the net and then, when it sort of hits the hits the court surface and then kicks up I've now I've got to return that, but I want to return the favour as it were, with my own tops been so how and why forces? Am I going to need to use to return that serve from the dark at that sort of Spain
How do we go about that? So the ball will be spinning in the opposite direction. You wanted to spend if you want to return it with topspin, so you're going to have to slight. You know: slice your racket up. The back of the ball. Two arrest the spin that Nidal gave it and then give it your own tunnel, I'm going to have more force and tops been them. What he has certain powerful me may well keep in mind the speed of the ball when it hits the court on the opponent side it's about through the quarters of the speed from which it was hit off the racket that the interaction with the grounds gonna take another. Order that speed off. So it's only go about half is fast when it reaches the player from the sea. So you have gotten a bit of a benefit from the the air resistance low in the ball downing impact with the court. So you're not exactly hitting a hundred and twenty.
Marylin our ball when it when it gets to you from the dolls racket. So that's interesting. This hope from a yet claim I got enough money or you you're all her, yes, but they will be pesos roubles lucky escape, keep him off of clay and he may have a chicken you are. It's so of fissile. Sam Karami wants to know this from Instagram, hey it SAM from Chicago I SAM Pace, and how much torque is apply to a tennis ball when it is hit with slice. Slice can. Actually, you know, get the money you see, Roger Federer, doing this, allow you can get up to four thousand Europeans are so with a really good slice, shot the killer, Meantime time the ball spends on the racket, it's only in the forty five millisecond range over for you calculating an average torque euro.
Getting about two and a half pounds foot pounds which may That sounds a lot when you think about exerting two and a half pounds foots distance, but keep in mind all is a lot smaller and the time at which that's acting as a is is, small. So you got a much smaller lever arm a much larger force on the ball. Generally He flies. You take an awful lot of pace out of yeah that ball and it just. What we flowed slow and a lot of times, a slices, because it's like you recovering recovery shot. You know, sometimes it's if you're closer to that, it's a really smart killer. Shalt, that's true cause! It takes its. It takes them, Does the slice slow the ball down, because that's what it looks like when these guys are playing it looks like the sly slows the ball down in a lot of times. It ends up looking like a drops You see the other player rushing toward the net to try and gotta. Ask the professor yet doesn't want you now.
Serve your giving it if you serve with pops and you can get an added bounce. One say a hard core clay grass. It it'll not have that quite as good a jump off the court, but if you back spent on it. Then you really gonna dead, deaden the ball when it hits the the court frictions, gonna, really dead, the jump off the court, gotcha correctness quest, I think it's Tyler men. I have noticed Tyler men on Facebook, and this is kind of like the the ballroom question. How fast The tennis ball be traveller minimum to go through a racket out loud ok so he's one of those whose who's gonna, there, the and Michael Phelps, or the sharp right it's out of those caught a question like so if you're playing with cyborg
and he and hits first what if he hits the bar to you hard enough to go through your racket. That means it should have gone through this racket. Well, of course, depends on if your swinging, your racket, when the Balkans I mean, if it, if he setting a stationary ball hard enough to get it up to the speed break. Your racket you gonna hold your racket still were you gonna try to hit the ball. So if you try, the Bali effect is gonna, be even greater and you dont need quite the speed Saturn at the questioner means Tyler means at the the racket stationary and let's go with language learning a shot unlucky. So here's the thing: let's go with regular human being served?
roughly on the dark. Ok serves the bar not show refers, can be happy with you calling in regular tat. I gotta tell you know where he may not be what it's cool he'll get over an actual, but let's say that model serves right and then our cyborg comes and hit the ball in a regular swinging motion. How hard with that have to how hard would he have to swing tat to get the ball to go through the actual, brings or even to get stuck in the strings. Now, let's go Stop Mr Through gotta eat. Just last April a ball on the net you're getting something like, let's say about seven strings in each direction, that are gonna be really in contact with the ball. And if you look up some of that, tensile thanks for the strings that are used I'd be around a hundred forty pounds or something said Edward. You could hang that much weight from a string before it starts to stretch and break, and now, if you take those
fourteen strings and assume they all had a hundred and forty pounds you're getting near a ton of force nearly two thousand pounds, but of course that's not quite how it works because the sinner strings, you're gonna assume a lot more that force than the ones near the site of the ball. I think you're gonna need something in there turn fifty two to undermine our range for the ball, before your actually gonna snapped the stream. That's it was, I know we're on our way to that area. I gotta terrorism is the way to go. This guy who knows, but so that's so you would. To get up somewhere around two hundred miles an hour. What would it take for the ball itself Kendall to not be able to withstand do you have any information on this? I think the ball can take a lot more force. I mean I've seen you know, videos of people put in Bali, in various compression devices where you get. You know ten thousand pounds or some crazy, I'm out of here for
on the ball. If we're like marriage, that's called marriage, yeah yeah. But you know I can trust you nothing you're gonna easily be able to do by putting it in your hand in breaking it. What you see in some movies question: I lie Matt Moose on Facebook. Why do tennis ball come in a vacuum? Sealed? Can So he refresh what is this? You quickly get either through Genesis, you get about what Maria balls and I can- and I like a Pringle size, king at an you, open the the top, and you got this pull tab and the reason is the rubber. That's making the outside of this tennis ball is very, very slightly permeable to air, and what that means is that the air inside the under normal atmospheric conditions is gonna start leaking out and if you
just leave these balls in an and pressure eyes can like that Sid. A short store shelf four months you open up the cannon. All are gonna have lost a lot of their internal pressure gate basically getting to atmospheric. So you have a dead body. Case knows. You just got us taken to school Yemen has I never knew that that's cool tat was an area also confess it gave us fabulous answer. We will take first break when we come back more of your cosmic query: questions about tennis, ball, fuzzy, poles, spinning and chop marriage break up, hopefully not be actually. Hey I've got a little secret for you
I'm gonna. Consider singing all of the ads on this show there's just one way to get out a hearing. There go to patriarch arms last startled and supporters at the five dollar level or higher to listen. The star talk ad free. You can download all current episodes into your favorite park has player and never hear another commercial on star talk ever again. You will definitely not have to hear me seeing if you're supporters Patria Dark coms. Last our talk, radio, I mean I'm just thing and I mean just saying.
Thank you very rightly said this is playing with scientists. We looked at the balls you spin and the freshness of a three year now it's time to take a look at the rackets themselves which have plenty of interest, particularly when it comes to friction. I'm gonna stick on this point and its milk. It and, of course, the power they import to a tennis ball so check our next question, but first reintroduce August. Today. Yes, of course, is Professor Eric Gough from Lisbon College in Virginia and the author of gold medal physics possessed of sport sites. I've porn recommend is a fabulous fabulous rate. Oh I'm just saying on next question
and he was very real from the atom club instalments. The Newton in the United Kingdom. Do you know where that is? Yes, it's in the candour said that we see a well look at so this is why he's a professor, because he knows that light back, so we're stores, ok dose it very South South West England. So you go if you think on the south of England, so you can't Sussex Hampshire, Dorset. Ok ever current was so that's way with the extra towards its way out I mean toss, it is one of those pretty is places in England or Britain. For that matter, however, the atom club. I'm just thinking, there's a nearby town called Branford Forum, and I'm just one bring. If there's a rival club called the up an atom club, because this,
creates this little rivalry, but anyway enough of my ramblings about Terry idea. Is there any evidence that grunting, like you're, giving birth to a pineapple helps generate extra power in your swing? Why on earth he went to pineapple, I suppose I know really dresser yours while giving through a pineapple that really takes me back to a South park episode with Paris Hilton, but when I married generates from what taking now is the grunting ethical Vinos like Monica sellers, Players, you ve done that re that coaches, some of the coach Isn the granting is a way to cut a time the release, the energy with in the body with when you hit yet. The analogy I like is that you in karate we use here, you know, and in Chrome Magog class Cropper got physics is the subject of manner
book we use or going out for visa. Well done, I wait when you patched thing and yet a wish that there's a negative to this issue although it could be positive from the point of view a person is languages. It messes with your to They don't like to hear the granting a distraction from yes, that's Muskie opponent, as the funds I have to tell you to that when you sit in the Stadium, it's a distraction as a fan. I'm sorry, you know, because it's it's a little much when you listen to some of these players get into it's just that you know it's very and it's only actually quite accurate yeah, I gotta tell you can be a little like if you let your mind wander, I'm just saying which obviously you have yet might forget. Your address, an issue that the tennis and you went somewhere you and me
he went to birthing upon its. It's a little work could be disturbing and distracted, really bad allergy, ok, we ve lost jobs for a couple of minutes, all continued silent or right. Here we go profess up his full name. Mark Eric Spence questions from Facebook. For obvious reasons, tennis serves and hits are faster with longer racquets, but at what point would the wreck be too long and the extra talk required would provide diminishing returns. So we have already had the larger heads, racket, So now Dignan, it's gonna, you gonna turn up with the Monty Python, ask giant tennis we need to gain from the stands yet. So what's the limit where, where just how I shouldn't we go there, looking at the idea,
the international TAT Tennis Federation rules set the limit of twenty nine inches, typically players or in the twenty seven to twenty seven and a half inch range These racket, sir, about nine fourteen ounces, yes and nearly a pound, and the problem is, of course, you may, if you were to make it too long now you're making the racket heavier, so you are going to be able to more talk on it. But it's also gonna cost you more energy to swing your racket, see you're gonna, get tired faster. So like John, is no, whose what six foot eight six foot nine crap, you imagine giving him a regular size, tennis record. It would look like a table tennis paddle, so he's gonna have naturally longer racket because he's got these nets. A longer leave, so there must be some room for the bigger tall apply as to be able to have longer rackets welcoming tolerable,
there's often have an advantage and a lot of sport ray you saying, oldest tall, you get Randy Johnson, throwing off the pitching mound. I mean basketball players. Obviously, so you know that at added ability to increase to work with you're, just natural, eight or arms length and used when you're gifts You cover more of the court just because your natural tall, we have to recognise that you ve got that wingspan right, so you know you're not having to shuttle across the baseline so much to get to it to stop. That's in the corner. You just reach out that wing pop. Very was back again just arm strength, so is there a place where it can be too long because he talks about diminishing returns? Is there a point where the length of the racket actually is a detriment? Well get? It depends on the player I mean. If you you're an amateur you don't wanna, be using at a meeting of the piece of equipment. That's a little too big. For you.
If you're swinging, something with more mass, because its longer there's an end. The cost of that. Every time you swing that rackets, gonna consume categories in your body, so you're gonna, have to take that into account. If you're gonna be playing a five that match over several hours, as a whole of different can type a science than because its conditioning, fitness and muscle strength are moving on to the next question summit Tina from Facebooking Barrington Illinois. Many players choose to use shock absorber on their strings, they range and the size and shape, but all seem to functions. Finally, how are they small, rubber esque pieces able to reduce the shock, felt while hitting the ball, and it goes on to ask? Are there any performance benefits to using minus sign from mere play? A preference, so first of all, you're gonna have to explain what is a shocking.
Is that the little rubber grummet stay. I actually so we how's the string at the at the rim of the racket. So in on a racket on the record head, you will have a sweet spot. Then you have a point of precaution and somewhere along the line and sort of the the balance and everything, but let the professor explain rather made because he's the professor and obviously I am not view put some Mass on the racket- you know just little beat or anything just any kind of mass on a string if its vibrating in you ve put mass on it than the vibrations gonna damp and much faster, there's more inertia, there's more mass you're trying to swing back and forth, but the the what the shock Georgia, there's little grom. It's really do. Is they get rid of the paying? So when you hit the tennis ball with them Racket. The stream vibrations are caught up in the five hundred to six hundred hurts range. So we can hear those is like a paying if you pay,
The little grounded on their the little shock absorber that tends to dead in the head, and it sounds more like a thud, but it's not gonna you with the vibrational energy and the racket cause most that's actually in the frame, and the reason is the frame is about twenty times more massive than the strings. So what's really damp and Out the energy and the racket is your hand. It's not the little grom its or more for the South than anything else would not really gonna save your hand. Merchant willows delude shock absorbers affect this spot, I know the size of the racket head is increase. The size of the sweet spot in play is love that, but does it have any effect in that sense? man that much. Yeah, almost around with you, don't get a real change in where the sweet spot is sold in really the two too
dampen the vibration of the racket. During these high intensity collisions with bar you, you really would have to have some kind of material like tempered foam or something like that on the grip or what would you do too too to reduce that is really what I'm asking. So if you hit in the remainder there in yet to sweets, I mean there's a vibrational knowed and then a little closer to the throat is the centre of percussion. Now one of the vibration it is worth he hit the ball there, you don't get any vibrations. You get a little bit of a shock in the hand. If you get at the center for cash men are not too far apart, so these early spots are very close together, but you get Us all vibration at the center percussion, but you don't get any shock in the had, so it that big
spot in the middle of the racquet, where you trying to hit the ball is going to keep the vibrations low on the hand. Now the Powerpoint is much closer. The throat more the centre, the racket. Down on the strings away from the tip in then throw to the stream bed rational player, are you actually looking at a ball got to feel that even if you get a lot more power from your shot, wow and so our players, cotton sense of this when your professional player, are you actually looking at a bar and making the mental calculation, even though this bomb baby coming at you at a hundred plus miles per hour? Are you actually making an egg, and I assessment, where you're trying to get this ball directly in the middle of this racket, so that you can get this sweet spot
Oh I'm sure they have an intuitive physics of where they wanna hit the ball. On that racket, I mean that this is a piece of equipment, that's in their hand for our the day practicing for years and years. So now, a very, very good feel for where that balls gonna hit the rat when their swing. If I relate that to my playing dies in soccer You know the to execute a certain pass. A certain shot required a certain scale. Now, if its across court volley, if it's a slice, if it's a top spin return- and I need to place that all directly in the tram lines. On far far, I have been playing doubles or just in that corner, because now two shots later, I'm gonna kill my opponent I have to be able to dial up a certain series of shots in the techniques that are in there that I will have as the professor
I have had this racket in my hand, hour after hour after hour week, month, year after year, I'll just be thinking this one pop, and I won't be thinking about the calculation through my brain to my body through history red there and that's what you're saying you guys it's about programmes, its programmes reaction is what it is through through and they experience. Then I get to the point where Opponent knows: I'm gonna dial up this shop right, so I just throw the eyes so I am now looking at that far corner and then I'll just cut it to the other side he will follow my eyes or disease participating what you're accessibility for now it now you get to the real genius act with these guys are calculating that your calculating. How can I didn't against your calculation and it just gets better and better and better? And you know what would you do
said. There is such a fascinating part of so many professional sports, and that- and that is when you talk about watching the eyes and so when in an intense, it's like when you see a Cross Court Cross Court shot, and then you see the return which I'll, be back across the court, but it goes straight down the line and its end. You see to it that the guy who made the crusts goes just like damn it got me. He totally got me and the same thing and football where you hear line backers, talk about watching the quarterbacks eyes or we are like how good do you have to be to be on a level with you playing this sport and reading somebody's eyes at the same Remy. It's it's in they won't just read the eyes they will now the body language, because if there really that sharply in tune mentally, they will know the potential is to go down the line right or across
so now, though, the eyes are one read: that's one tell the other one is body language. Does that I have, I have to put my body and a certain shape right to play a certain shot. So therefore, the immediately calculate what's wrong with this picture, and it's it's that I said the levels get better and better and aspect tighter when, see Nedda when you see federal when you see Mary, when you see jock, of which you are watching guys that are so good at every single agree. Absolutely by two quick points there that even the best of the best you're gonna see enforced errors. I mean you. There let it be able to hit it exactly they where they wanted every single time and the second Is there there's risk? That shown. The eyes cannot follow a pitched baseball. You know that four tenths of a second right- it's travel it. So it is the same with a fast moving tennis ball, I mean they're not able to actually track the ball
every little millimeter of its trajectory emulate they'd, there's enough intuitive physics here, the biomechanics that they train themselves, for years to know where to be where to react to a certain The sound of the ball coming off the reality is another, that's a fabulous point, professor, because now it becomes essential thing. You're. Looking and you hear you hearing and you look your eyes. You looking body should be looking at noises and also to different things and also when the noise of the record is another tell is like member, you said you're off again, You see that that thought on a home run right where you are, Go head up this one's leaving the power. You know that you know that the same with Tennyson, that's how that's how high level these players eyes fabulous Well, it's a game of inches and grunting balls and gas. It is very, very sensual. We are going to take another break
we didn't get, I think, just by mainly for trucks, benefit a shower we haven't got gods your questions. I do apologise. We are limited in time because, once again, big thanks to everybody, so many questions we do our best to to cover as many as possible. We are going to take that break the good professor, professor, Eric Gulf author of Goma, because it will be staying with us, we'll be back very, very shortly- will touch on courts and surfaces. Your question was in that category: stick around Europe
we're back yes playing with science cosmic. Where is the tennis special bill by Lichness? However, big think out, every single one of you, you see your questions and hopefully we put them out of the hat. So we ve got the professor guph with us still, so we would have him unlock the answers in all of your question so right, courts, services and, more so chuck next question gear. This is Joe guess, you're from Facebook and he's from Barrington Illinois who are second from parents, never know how number two wants to know this
players slide on different surfaces, clay grass, hard courts. Is there a different techniques used or is there just more force put into the slide to overcome a greater coefficient of friction between the shoe and the surface, thanks also to other, are they using different foot Where for these different services, I mean that we would have to. I would say I get out that sounds you re professes answer have professor well, so grass is certainly the fastest surface. The grass is a little slow you get a little less friction on the ball. The balances are quite as high, We are seeing a match on grass. The players tend to be using a lot more speed. In power? The rallies don't last quite as long. If you're, a big powerful, sir you're gonna love grass, the hard courts usually have some kind of synthetic, girl, acrylic layer sitting on a asphalt or concrete base
those are caught up in the middle between clay and grass? Clay is certainly the slowest you have a lot of court friction on the ball that you get these high bounces end. The players use a lot of top spin and then sliding on clay. You have all the particulates down. On the surface of the shoes are able to slide a lot better. The island, the clay. Although a facet of my new research that was just published, is we're saying out. Real would now got a pretty good explanation for why you're seeing sliding more on hard courts we come on. Man drum roll new research. This was, this- was work. I did your spent at the University of Sheffield. So many of our UK listeners I check out Matt Car at the University of Sheffield and anyone in the U S is looking to do some sport science check me on your Lynchburg College and we're doing right now is we're looking into
do treads and what we found based being some rubber with holes in it is, if you break these little dimpled holes, theirs critical area, a critical ratio of the area, the holes to the total contact area. And if you go past it, the static friction drops by more than eleven percent on a hard court so that that means as if Europe, if you put your shoe down and it not quite sliding the static friction- is what you feel once it starts to slide. We call it kinetic friction, but it can reduce that static. Friction you can initiate sliding much faster, basically like a race car tyres. So you you have different grades, so you go from slicks. To medium to wet weather tyres and as accordingly, but I didn't with the holes in the rubber? What size of holes are we talking about here cause? So if you can get something of order? Twenty five percent of a contact area, the shoe
to have kind, a dip or a whole area. You're gonna get a reduction in this slide. Friction you know to initiate the slide. Quicker if you look at Roger Federer, he uses a Nike court. Zoom use you'll, see exaggerated and deeper cut hearing on the outside of the shoe Novak Yoke of acres. Really what one of the pros that kit makes a lot of use of sliding is an incredibly athletic player, absolutely Maybe he's got an audit ass. No fact pro named after him, you'll see these do a deep groups particular section on the outside of issue? Lee Murray, you know from from Gary's the words I mean he's gonna have a lease left out. He doesn't go to underline. How do you know he's got an under armor charged ultimate annual noticed. It's got like four cut out sections on the outside ed. So again the gaps are gonna.
Been slide. I even younger players like Diego Schwartz men, uses a feel a cage delirium and it's quite from the US icily issue right because that yeah yeah, because it actually sounds like a very dangerous dog yeah the fee, lock, its delirium berry society cyborg. Yet it's interesting when you talked about holes, in the social issue, because added made a shoe for soccer, but a a flat. You noticed, studied or created chew back in the sixties. And it had so the suction cops throughout the soul and at an you when you sort of talk about hold but you're, not talking about that sort of thing, it's actually The opposite! These are, I mean we're torment like dimples. Never so you your turn back grooves or some kind of depressions in another.
Rubber into the soul of the shoe, and the idea is that it will start sliding. If you have enough whole area to initiate this slide, you can go out and buy a Wilson Glide shoe and you ve got these to slide plates in each of the shoes, and you can get practised on sliding with that, but all of these shoes that the pros or using on the hard courts, the ones that are taken advantage of sliding you're gonna notice some gap in the tread, the get a little wider than some of the traditional herring bones. The only thing comes thinking now is, if you start slide on a hard core that sole, better, be fire retardants Gonna get really really hot shoes. Ok! Well, in that case, I am all for it, because nothing would make me happier than to be at a professional this mess and uneasy somebody's it for that's right since somebody's feet burst into flame God,
yeah, that's why they said that they also swaps use out. Sometimes yet the whole new meaning to the displays on fire, had put baby. I've read your laptop about ok. So now, Julian genes from Facebook wants to know this. If we make a tennis field with moon, does will have the effect than rolling Garros tennis feel. Will the balance be better or worse. Compared to other surfaces. What's a roman Garros Teghmus Field, Roller Garros was a famous french tennis player and run on garage. Is the number one tennis court and complex in France in Paris, and it is where the French would have read later this answer: Professor Moon dust, tennis court.
When we go near the majority. A moon dust is, is a silicon dioxide glass and its come about from a bunch of these meteorite collisions with the surface of the moon, but it's actually pretty nasty stuff. It's it's very abrasive. Somebody astronauts complained about it starting to get through this suits, it also sticks to stuff ill, stick to the ball balls you're, playing with the shoes, the clothes and the play. What really want to breathe and at its got some iron area. I mean it's, not not something you want to be playing. Tennis Ok, it's a punishment. It is, as though arrive. If, if you being punished, you ve been sent to the Moon Dust Court to play tennis
sure yeah and if you're on the moon and the gravitational poles about a sixth, what it is here. You're gonna get some pretty long shots, you're, gonna big court to Ya Professor Good SIG way. Well done, Sir John Mc Killop on Facebook. He tied straight into this right. What's the biggest thing in the solar system from which a bull hit by the best tennis broke could achieve escape velocity love to show Joe. Thank you so much, and we love your question. Yes that, but now what do you mean by? What's the biggest? They don't know who you he or she? What? Yes, I think I can. I can. I can answer that, so you know you're gonna escape earth. I mean not even accounting for air resistance. I mean just to get off the gravitational tiger. The earth you're gonna need about twenty five thousand miles per hour. Launch you're gonna need set than a little more just to get past the atmosphere. So the idea-
is. Can you find something small enough in the solar system that you could hit him? You know nice, strong Tennessee earth and it could actually leave the object without ever coming back and I you know, I had to check what the world record is on. Tell us serve its Australia. Sam growth is a hundred and sixty three point. Four miles an hour and twenty twelve wow say that again, that's incredible! A hundred and sixty three per hour on a tenant serve,
So, let's just say we're not quite that point: we're gonna hit your hundred fifty miles an hour. The escape speed, actually scanner. Squeals are sorry scales with the square root of the mass of the object divided by its radius. So you need to find something out there that is going to fit what you need. The earth is about twenty thousand time that ratios about twenty thousand times do big, though I actually found a moon of Saturn Hyperion that'll do the trick. If you serve a tennis ball pattern, fifty miles an hour, it will escape Hyperion Hyperion, one of these little chaotic, tumbling moons of Saturn than it's only a couple hundred MA,
was wide in one direction, may be a hundred and twenty some odd miles in another direction, and you can actually get the ball to leave that little maid of Saturn so less parallel bags and had had a high period country club, nay, you recognize it do. I can impose enough, we ve lost another boone, might be able to find that a school will National yea sudden, you find a whole lot of tennis, both in orbit around satin another lovely day here the Hyperion tennis Club well we're out of balls because we keep losing them escape velocity. Her well anyway, we have to put the membership. Let's move on those gown was actually a very fascinating grandiose. Yes, this Mr Gee, and he comes to us through Twitter ACT,
I atomic sign nerd, and he wants to know this. If we put players into suits on a court inside of a vacuum dome what happens to the flight dynamics of the ball next gentleness, anyone mister, you're so badly clever? Well, that's it actually really fine little thought experiment, let's get some guys into into space suits, let's put him in a vacuum, and then let's play some tennis, we gonna look at what kind of game are we looking at that point in a week, We do know now that from our first segment that there's a lot of a dynamic that will lose when it comes to the fighting this of the bomb. But what are we looking at professor well you're, also going to lose sound cause. You're not gonna, have sound propagating an event.
Give man. That means I can't listen to all those wonderful grunts people, birthing pineapples, unless you ve got like you, know, a microphone inside the helmet and then workers are something in There- that you can hear the other plainer. Bringing the sound effects will make it Bob Sayer resistance is obviously gone, so the the balls are gonna be moving a lot faster, you're not going to be able to get any effect from spin you're, not going to have any err. Twenty two whip around that ball and have that NICE Magnus effect help curve the ball so forget, all those nice curbs on your shots so The result will be a really boring game of tennis is basically what we are saying here. I mean it
you could serve a hundred fifty miles an hour in the drag force is like nine times the weight of the ball. I mean it's a huge effect on the ball, so you take out the air. I mean it's a much much different taken. Do you think that kingdom tennis he's going to catch him well think about the ball, moving a lot faster and your ability to get to it wearing a big suit. Yet I said it's really boring game of Tennessee you serve. Basically, everybody just hold serve, you serve and the other person watches the ball go by. That's that's the way to get hastily walk, walk, walk Hitler, Kidnap, ok time for one more just one more just the one more Kevin Moynihan go and ensure Heaven Moynihan wants to know this coming to us from Facebook, and you have to answer this. Professor scientifically scientifically Kevin says this: how come I can't stop laughing at that picture of prompt trump playing tennis problem
This is funny, is a picture of Trump Playing President's raw data dead did at the open. I didn't even need two days to come up with a second region and I live in our from Charlottesville? Oh, my god, you doubt I gotta tell kudos was it was excellent. My progress has got possesses, got ourselves as proven once again present Eric Gulf, the author of gold metaphysics. Thank you yeah. So much for your time. Thank you for bringing us the the answers to so many of our listeners questions. Thank you to our lessons. This show does not exist without you and your questions have been put, and hopefully the answers have been fulfilling check. What about a great show like say: you're, not a fine professor! Thank you. It's more ways informative and entertaining when you are on and to be on their man? I can't wait to hook,
with you at the Hyperion Tennis Club, long long long trip to get their husbands say: yeah, that's that's! That's that's quite a ways: isn't it went round the corner, that's it for those show hope I've enjoyed. It hope you tune into playing with science in the future. We do the fourth, your company. Until then tat I Diet, Bardell lay I'll drop the organs. Which you can listen, the star, talk commercial free, joint star talk on patriarch for as little as five dollars per month and the ads will disappear, learn more at patriarch dot com. Last star talk: radio.
Transcript generated on 2020-01-20.