#ICYMI: Cosmic Queries: Tennis Special Edition

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=2 GooglePlay Music: https://play.google.com/music/listen?u=0#/ps/Iimke5bwpoh2nb25swchmw6kzjq SoundCloud: https://soundcloud.com/startalk_playing-with-science Stitcher: http://www.stitcher.com/podcast/startalk/playing-with-science TuneIn: http://www.tunein.com/playingwithscience NOTE: StarTalk All-Access subscribers can watch/listen to this entire episode commercial-free. Find out more at https://www.startalkradio.net/startalk-all-access/

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:11Gary O'Reilly?

  I'm Gary O'Reilly

• 0:12Chuck Nice?

  And I'm Chuck Nice

• 0:13Gary O'Reilly?

  And this is Playing with Science Yes, today is a Cosmic Queries tennis show, where we open the floor to our StarTalk Playing with Science family, and let them pose the questions. So, if you ever wondered why your balls spin, and why you must always keep them fuzzy...

• 0:34Gary O'Reilly?

  Yeah, I knew you'd like that.

• 0:35Chuck Nice?

  Come on now, you know I can't do... 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 news spin on a never-ending string theory, you are in the right place, because our good friend, Professor Eric Goff from Lynchburg College, Virginia, and author of Gold Medal Physics, is the man to unlock the answers to your questions. Now, let's get back to some fuzzy balls that spin.

• 1:02Gary O'Reilly?

  So Eric, good to have you back. How've you been, sir?

• 1:05Speaker 02

  I'm doing great. It's good to be back. How are you, Gary and Chuck?

• 1:08Gary O'Reilly?

  We are fabulous, yes.

• 1:10Chuck Nice?

  Good to hear you.

• 1:11Gary O'Reilly?

  So what have you been up to?

• 1:14Speaker 02

  Well, our classes begin in a week, so I've got about three more days before I need to start preparing for them.

• 1:21Chuck Nice?

  It's good to see that those kids are getting a quality education as you last-minute their curriculum professor.

• 1:29Speaker 02

  Well, I gotta get all the research done before the classes start.

• 1:32Chuck Nice?

  Okay, I got you. Hey, by the way, now that the Tour de France is over, for those who know that you are the person who does the modelling, how did you end up ultimately?

• 1:45Speaker 02

  Oh, we did a really fabulous job this year. Our last stage, we missed by just 11 seconds, so we had a fantastic prediction set. 15 of our stages, we did better than 4%. 11 of them, we did better than 2%.

• 2:02Chuck Nice?

  Wow.

• 2:03Speaker 02

  So, we had good predictions this year.

• 2:05Gary O'Reilly?

  And you nailed Chris Froome from the start, anyway.

• 2:07Speaker 02

  Uh, we had, yeah, I mean, I kinda figured Chris Froome was gonna be the, the guy to beat and no one could, could beat him. So he got his fourth.

• 2:15Gary O'Reilly?

  Can't touch this.

• 2:16Chuck Nice?

  Yeah. And by the way, before we go any further, so how many does that make for Chris Froome?

• 2:19Gary O'Reilly?

  Three in four.

• 2:21Chuck Nice?

  That's three in four?

• 2:22Gary O'Reilly?

  Yeah.

• 2:23Speaker 02

  Well, he's, it's his, uh, fourth total, but third in a row, right?

• 2:26Chuck Nice?

  Third in a row, but fourth total. Okay, cool. And how many more before we say he's better than Lance Armstrong? Just as a, just as a, uh, point of interest?

• 2:34Speaker 02

  Well, Lance is officially one, zero, right?

• 2:38Chuck Nice?

  Damn, that hurt. Ooh, Professor.

• 2:41Gary O'Reilly?

  Below the belt blow from the professor.

• 2:44Chuck Nice?

  I love it. Hey, well, let's get into our.

• 2:47Gary O'Reilly?

  All right, let's get our first question. Mark Miller from Halifax, Nova Scotia on Patreon. This is how you pose a question to get it on Playing with Science. Love the show, says Mark. So I read that the fuzz on the felt cover of a tennis ball helps control its speed and bounce. Would the fuzz itself have an effect on the effects of spin? We see more amazing curved shots. So Professor, I'm gonna knock that over the net. It's all yours.

• 3:18Speaker 02

  So the fuzz actually increases the cross-sectional area of the ball going through the air. So, uh, you get a little bit more area than if it didn't have fuzz. You get a little bit more air drag on it. So it will slow the ball down a little bit. Uh, as for the spin, the fuzz actually does help with the spin, but mostly, uh, for low spin balls. Uh, when you start getting up to high speeds and high spin, uh, the fuzz tends to lay down on the ball's surface a little bit more. And you don't notice it quite as much when you get really high spins and really high speeds.

• 3:55Chuck Nice?

  So, um, when you, so let's say you take the fuzz off of the ball. How much would it change the game?

• 4:04Speaker 02

  Well, you're gonna notice it more for the low spin, low speed shots. You're gonna get a little bit less of a curve. You're also gonna get a little bit less of a bounce off the ground if you have the fuzz on there because you get a little bit more friction.

• 4:21Chuck Nice?

  So you get less of a bounce with the fuzz?

• 4:25Speaker 02

  With the fuzz, yeah.

• 4:26Chuck Nice?

  Gotcha.

• 4:26Speaker 02

  And if you take the fuzz off, you're gonna reduce the air drag a little bit. So the balls are gonna be moving a little bit faster.

• 4:31Gary O'Reilly?

  Now, this touches on a question from James Arnold from Facebook. He says, why is tennis played with fuzzy, bouncy balls, which you've already addressed? Is the fuzz important? Yeah, we've touched on that one. Or could it be shaved down? Now Chuck, I thought you'd be all over this because this is in your ballpark, as it were.

• 4:48Chuck Nice?

  No, I mean, seriously, first of all, I am not about shaving the fuzz from the balls because the way I feel is though it gives the balls a juvenile look. And I, for one, like mature looking balls.

• 5:04Speaker 02

  Well, that does add an extra wrinkle to the problem, doesn't it?

• 5:07Chuck Nice?

  It certainly does.

• 5:08Gary O'Reilly?

  Do not encourage him, Professor, please. We've got a long way to go in this show. What's the sort of coefficient of drag and all the rest of it that this fuzziness brings to a tennis ball?

• 5:20Speaker 02

  When you put fuzz on a tennis ball, what it's actually doing is it kind of thickens the boundary layer of air that's around the ball. And the flow of the air around the ball looks a little bit more what we call laminar than it does turbulent.

• 5:35Chuck Nice?

  Say that again now, can you explain those two things? I missed that.

• 5:38Speaker 02

  So for low speeds, the air separates behind the ball kind of at a big wake. When you go a lot faster, the air gets wrapped around the ball a little bit tighter. And the so-called drag coefficient drops. That was the drag crisis we've talked about on an earlier show.

• 5:55Chuck Nice?

  Yes!

• 5:57Gary O'Reilly?

  You've started again, Professor.

• 5:59Speaker 02

  So the fuzz actually will thicken that boundary layer and move that drag crisis to a higher speed. So you actually get a little bit more on the drag coefficient, a little bit more area. So there's actually considerably more drag on the ball with the fuzz than if you didn't have any of it on there.

• 6:16Chuck Nice?

  So it's just kind of the opposite of like a boat in a lake?

• 6:22Chuck Nice?

  Like the faster the boat goes, the bigger the wake is. So you're saying the faster this ball spins and goes through the air with the fuzz, the smaller the wake behind it.

• 6:31Speaker 02

  Well, with the fuzz, you actually get a bigger wake.

• 6:34Chuck Nice?

  Oh, I see what you're saying.

• 6:35Speaker 02

  When you cross that drag crisis into the turbulent regime, the wake would actually kind of wrap more around the back of the boat into like a narrower wake.

• 6:44Chuck Nice?

  Got you.

• 6:45Gary O'Reilly?

  What's interesting is, we've seen this type of tennis ball for, I can't remember how long. And you're just wondering, the people who introduced this type of tennis ball into the sport, do you think they would have been all over the physics of it and thinking, right, this is how we progress the game?

• 7:05Speaker 02

  I don't know the actual history. I mean, I know with golf balls, they started with smooth balls, and then the aristocracy noticed that when the bourgeoisie were playing with the used balls that they were discarding, they were going farther. So, of course, now we dimple the ball. So I imagine there was some trial and error involved. I mean, if you remove the fuzz, I mean, how fast do you want the game to be? I mean, how few hits do you need in a volley for it to be good tennis?

• 7:34Gary O'Reilly?

  How fast a serve would you have on a completely clean surface?

• 7:39Chuck Nice?

  Well, that's funny, because 33Kyleford from Instagram asked this question. How fast does the ball have to spin for the spin to affect the trajectory? So at what point does the ball have to speed up so that the spin can create a different, or create movement?

• 8:05Speaker 02

  Well, so the, I mean, any type of spin is going to give it a little bit of a sideways movement. You're always going to have a little bit of this Magnus force for even small spin. The typical angular speed you see on a tennis ball tend to be somewhere between about 16 revolutions per second and 80 revolutions per second. If you like thinking about RPMs, that's somewhere between 1,000 and 5,000 revolutions per minute.

• 8:30Chuck Nice?

  Wow, not bad.

• 8:32Speaker 02

  When you're getting a serve well in excess of 120 miles an hour with a lot of top spin, I mean, these things are really spinning. And what the spin actually does, the top spin for a serve, it'll increase the available range to something like 2 and 1/2 to 4 degrees. And that gives the player a little bit more room for error when you're aiming for like the sideline, or sorry, the center line or the back corner for a serve.

• 8:59Chuck Nice?

  Mm-hmm. So, so, so.

• 9:01Speaker 02

  I was gonna, go ahead.

• 9:02Chuck Nice?

  Go ahead, Professor, yeah. Keep going, Professor.

• 9:04Speaker 02

  Well, another nice thing about the spin is that when it hits the ground, the ball is spinning. And if I could show you, I would. But when the ball is turning and it hits the ground, the ground imparts a significant amount of friction on it, and it can actually kick the spin up. It can double the spin. So you get a lot more spin off the bounce. And that can play havoc with some inexperienced players.

• 9:28Chuck Nice?

  Absolutely. Now, can you just, I mean, because now that you've opened this up, I really just am asking for myself, can you explain, because that seems counterintuitive, the fact that the ball hits the ground, you would think that that would slow the spin down, that in fact, you use the term friction. Normally, whenever we think of friction, we think of something being slowed down. It goes into retrograde. It goes into retro. So, how exactly does it kick the spin up? It's very interesting.

• 10:00Speaker 02

  Well, try to imagine a ball coming into a surface at an angle and it has no spin. When it hits the surface, the ball and the surface are gonna rub against each other, and you're gonna have a frictional force in the opposite direction of the way the ball's moving. So the ball will actually leave the surface with spin. And you can do this with, if you ever have a super ball.

• 10:22Chuck Nice?

  Yeah.

• 10:22Speaker 02

  Just take it and spin it and drop it straight down, and you'll watch it kind of, it'll look like it's walking back and forth with each new bounce as the spin changes direction.

• 10:31Chuck Nice?

  You're right, you're absolutely, oh, that's great.

• 10:33Gary O'Reilly?

  Okay, so we've got this.

• 10:35Chuck Nice?

  I love how I just told him he's right, like, he's not a professor of physics.

• 10:39Gary O'Reilly?

  I saw it more as an agreement.

• 10:40Chuck Nice?

  Yeah, I'm like, hey, you know what? You're right. Like, I approve.

• 10:43Gary O'Reilly?

  So if you can imagine a Nadal serve that comes in at the sort of pace, we're talking about 100 mile an hour plus, but because he imparts so much topspin, it dives once it clears the net. And then when it sort of hits the court surface and then kicks up, I've now got to return that. But I want to return the favor, as it were, with my own topspin. So how and what forces am I going to need to use to return that serve from Nadal at that sort of speed? And how do we go about that?

• 11:17Speaker 02

  So the ball will be spinning in the opposite direction you want it to spin if you want to return it with topspin. So you're going to have to slice your racket up the back of the ball to arrest the spin that Nadal gave it and then give it your own topspin on the way back.

• 11:34Gary O'Reilly?

  So I've got to impart more force and topspin than what he has served up for me?

• 11:37Chuck Nice?

  Man.

• 11:39Speaker 02

  Well, keep in mind the speed of the ball when it hits the court on the opponent's side, it's about three quarters of the speed from which it was hit off the racket. The interaction with the ground's going to take another quarter of that speed off. So it's only going about half as fast when it reaches the player from the serve. So you have gotten a little bit of a benefit from the air resistance slowing the ball down, the impact with the court. So you're not exactly hitting 120 mile an hour ball when it gets to you from Nadal's racket.

• 12:12Gary O'Reilly?

  All right, so that's interesting. There's hope for me yet when I play him.

• 12:18Chuck Nice?

  I got my money on you.

• 12:19Gary O'Reilly?

  Oh, you're all heart.

• 12:20Chuck Nice?

  Yes, but they will be pesos or rubles.

• 12:23Speaker 02

  Just keep him off of clay and you may have a chance.

• 12:26Gary O'Reilly?

  Sure.

• 12:27Chuck Nice?

  All right, so official Sam Carani wants to know this from Instagram. Hey, it's Sam from Chicago.

• 12:36Gary O'Reilly?

  Hi, Sam.

• 12:36Chuck Nice?

  Hey, Sam. How much torque is applied to a tennis ball when it is hit with a slice?

• 12:45Speaker 02

  So slice can actually, you know, get the, I mean, you see Roger Federer doing this a lot. You can get up to 4,000 RPMs or so with a really good slice shot. The collision time the ball spins on the racket, it's only in the four to five millisecond range.

• 13:00Gary O'Reilly?

  Wow.

• 13:01Speaker 02

  So if we're just calculating an average torque, you're getting about two and a half foot pounds of torque, which may not sound a lot when you think about exerting two and a half pounds at a foot's distance. But keep in mind, the ball is a lot smaller and the time at which that's acting is small. So you've got a much smaller lever arm, a much larger force on the ball.

• 13:25Gary O'Reilly?

  Generally, when you slice, you take an awful lot of pace out of

• 13:29Chuck Nice?

  Yeah.

• 13:29Gary O'Reilly?

  that ball and it just just floats over the net.

• 13:34Chuck Nice?

  And a lot of times it slices because it's like you're recovering. It's a recovery shot, you know.

• 13:41Gary O'Reilly?

  Sometimes if you're closer than it, it's a really smart killer shot.

• 13:44Chuck Nice?

  That's true because it takes, it takes the, does the slice slow the ball down? Because that's what it looks like when these guys are playing. It looks like the slice slows the ball down and a lot of times it ends up looking like a drop shot. And you see the other player rushing towards the net to try and pick up the shot.

• 14:01Gary O'Reilly?

  Let's ask the professor.

• 14:02Chuck Nice?

  Yeah. Does it slow it down?

• 14:03Speaker 02

  So if you're giving, if you serve it with topspin, you can get an added bounce on say a hard court or clay, grass, it'll not have that quite as good a jump off the court. But if you've got backspin on it, then you're really going to deaden the ball when it hits the court. The friction's going to really deaden the jump off the court.

• 14:27Chuck Nice?

  Got you.

• 14:28Gary O'Reilly?

  All right, next question, I think it's Tyler Mene, if not, it's Tyler Men on Facebook. And this is kind of like the barroom question. How fast must a tennis ball be traveling at minimum to go through a racket?

• 14:42Chuck Nice?

  Oh, wow.

• 14:43Gary O'Reilly?

  Yeah, it's one of those, who's, who's going to get there, the end, Michael Phelps or the shark?

• 14:48Chuck Nice?

  Right.

• 14:48Gary O'Reilly?

  It's one of those kind of questions.

• 14:50Chuck Nice?

  Like, so if you're playing with a cyborg and he, and he hits, first of all, if he hits the ball to you hard enough to go through your racket, that means it should have gone through his racket.

• 15:06Speaker 02

  Well, of course, it depends on if you're swinging your racket when the ball comes. I mean, if he's hitting a stationary ball hard enough to get it up to the speed to break your racket, are you gonna hold your racket still or are you gonna try to hit the ball? So if you try to hit the ball, the effect is gonna be even greater and you don't need quite the speed.

• 15:26Chuck Nice?

  Gotcha.

• 15:27Speaker 02

  So I don't know if the questioner means, Tyler means that the racket is stationary and...

• 15:34Chuck Nice?

  All right, let's go with playing a shot. Let's go with playing a shot, okay? So here's the thing, let's go with a regular human being serves like a Rafael Nadal, okay? Serves the ball. I'm not sure Rafael's gonna be happy with you calling him regular. I gotta tell you, you know what, he may not be, you know, but it's cool, he'll get over it, I know. I'm sure. But let's say that Nadal serves, right? And then our cyborg comes and hits the ball in a regular swinging motion. How hard would that ball have to, how hard would he have to swing to get the ball to go through the actual strings? Or even to get stuck in the strings? Now, let's go through. Yeah, just blast through.

• 16:15Speaker 02

  If you put the 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 the tensile strength for the strings that are used, they might be around 140 pounds or something. So in other words, you could hang that much weight from a string before it starts to stretch and break. Now, if you take those 14 strings and assume they all had 140 pounds, you're getting near a ton of force, nearly 2,000 pounds. But of course, that's not quite how it works, because the center strings are gonna assume a lot more of that force than the ones near the side of the ball.

• 16:58Speaker 02

  I think you're gonna need something in the 150 to 200 mile an hour range for the ball before you're actually gonna snap the string.

• 17:06Chuck Nice?

  Gotcha. We're on our way to that. Yeah, I gotta tell you something, the way the game is going, who knows? But so that's, so you would have to get up somewhere around 200 miles an hour. What would it take for the ball itself to not be able to withstand that? Do you have any information on that?

• 17:26Speaker 02

  I think the ball can take a lot more force. I mean, I've seen, you know, videos of people putting balls in various compression devices where you get, you know, 10,000 pounds or some crazy amount of

• 17:38Chuck Nice?

  Yeah.

• 17:38Speaker 02

  uh, force on the ball before they break.

• 17:40Chuck Nice?

  That's called marriage. Yeah.

• 17:41Speaker 02

  Yeah. But, I mean, it's not

• 17:44Gary O'Reilly?

  That could cost you.

• 17:45Speaker 02

  It's not something you're gonna easily be able to do by putting it in your hand and breaking it, uh, despite what you see in some movies.

• 17:52Gary O'Reilly?

  All right, here's a question I like. Uh, Matt Moose on Facebook, why do tennis balls come in a vacuum sealed can?

• 18:01Speaker 02

  Oh, yeah.

• 18:03Gary O'Reilly?

  To keep them fresh? What is this?

• 18:05Speaker 02

  You typically get a

• 18:06Chuck Nice?

  That's why they're so delicious.

• 18:08Speaker 02

  Yeah, you get about, what, three of these balls in a can, and you're kind of like a Pringle-sized can, and you open the, the top and you got this pull tab, and, uh, the reason is, is the rubber that's making the outside of this tennis ball is very, very slightly permeable to air. And what that means is, is that the air inside the ball, under normal atmospheric conditions, is gonna start leaking out. Uh, and if you were to just leave these balls in an unpressurized can like that, uh, sitting on a short store shelf for months, you open up the can and the balls are gonna have lost a lot of their internal pressure, basically getting to atmospheric. So, uh, you have a dead ball in that case.

• 18:52Gary O'Reilly?

  Matt Moose, you just got us taken to school.

• 18:55Speaker 02

  Yeah, man.

• 18:56Gary O'Reilly?

  Because I never knew that. That's a cool question.

• 18:58Speaker 02

  That was a great question.

• 18:59Gary O'Reilly?

  And of course, the professor gave us the most fabulous answer. We will take our first break. Um, when we come back, more of your Cosmic Query questions about tennis, balls fuzzy, balls spinning, and Chuck's marriage breakup. Hopefully not. Uh, we'll be back shortly.

• 19:15Chuck Nice?

  Ball's gotta breathe.

• 19:19Gary O'Reilly?

  Welcome back, I'm Gary O'Reilly.

• 19:21Chuck Nice?

  And I'm Chuck Nice.

• 19:22Gary O'Reilly?

  And this is Playing with Science. We've already looked at the balls, the spin and the freshness of a three pack.

• 19:32Chuck Nice?

  Yeah.

• 19:32Gary O'Reilly?

  Yeah, and 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 it's gonna milk it and of course, the power they impart to a tennis ball. So Chuck, our next question, but first reintroduce our guest today.

• 19:51Chuck Nice?

  Yes, of course, he is Professor Eric Goff from Lynchburg College in Virginia and the author of Gold Metal Physics.

• 20:00Gary O'Reilly?

  The Science of Sports, which I can recommend is a fabulous, fabulous read. Oh, I've just seen our next question.

• 20:08Chuck Nice?

  Yes, and he is right.

• 20:09Gary O'Reilly?

  Chris Ryu from the Atom Club in Stirling Newton in England.

• 20:15Chuck Nice?

  The United Kingdom. Do you know where that is?

• 20:17Gary O'Reilly?

  Yes, it's in the country.

• 20:19Chuck Nice?

  It's in Dorset, isn't it?

• 20:19Gary O'Reilly?

  You see?

• 20:20Chuck Nice?

  Oh wow, look at you guys.

• 20:21Gary O'Reilly?

  This is why he is a professor, because he knows stuff like that.

• 20:24Chuck Nice?

  So where's Dorset?

• 20:25Gary O'Reilly?

  Okay, Dorset is southwest England, so you go, if you think on the south of England, so you go Kent, Sussex, Hampshire, Dorset, Devon, Carnwell.

• 20:36Chuck Nice?

  So that's way, so Dorset's way far south.

• 20:38Gary O'Reilly?

  I mean, Dorset is one of the most prettiest places in England, or Britain for that matter. However, the Atom Club, I'm just thinking, there's a nearby town called Blanford Forum, and I'm just wondering if there's a rival club called the Up and Atom Club? Because this just creates this little rivalry, but anyway, enough of my ramblings about teary eyed England. Is there any evidence that grunting, like you're giving birth to a pineapple, helps generate extra power in your swing? Why on earth you went to pineapple, I suppose I know really. Professor, all yours.

• 21:14Speaker 02

  Wow, giving birth to a pineapple, that really takes me back to a South Park episode with Paris Hilton, but.

• 21:21Gary O'Reilly?

  That's maybe where it generates from.

• 21:23Speaker 02

  What I'm thinking now is the grunting, you think of, you know, like Monica Selass and other players who've done that.

• 21:31Gary O'Reilly?

  Right.

• 21:32Speaker 02

  The coaches, some of the coaches will teach that grunting is a way to kind of time the release of the energy with, in the body with when you hit. The analogy I like is that, you know, in karate, we use kia, you know, and in Krav Maga class, Krav Maga physics is the subject of my next book, we use.

• 21:53Gary O'Reilly?

  Good plug, good plug professor, well done.

• 21:55Speaker 02

  When you punch something and you say, there's a negative to this, of course, although it could be positive from the point of view of the person who's grunting, which is it messes with your opponent. They don't like to hear the grunting.

• 22:09Chuck Nice?

  It's a distraction.

• 22:11Speaker 02

  Yes, that's right.

• 22:12Gary O'Reilly?

  As much the opponent as the fans themselves.

• 22:14Chuck Nice?

  I have to tell you too, 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, it's just like.

• 22:31Chuck Nice?

  You know, it's very.

• 22:33Gary O'Reilly?

  That's actually quite accurate.

• 22:34Chuck Nice?

  Yeah, I gotta tell you, it's, it can be a little, like if you let your mind wander, I'm just saying.

• 22:39Gary O'Reilly?

  Which obviously you have.

• 22:40Chuck Nice?

  Yeah, you might forget that you're at a tennis match.

• 22:43Gary O'Reilly?

  So you tuned out the tennis and you went somewhere, you.

• 22:45Speaker 02

  He went to birthing a pineapple.

• 22:47Gary O'Reilly?

  He did, yeah.

• 22:52Chuck Nice?

  It's, it's a little, it can be disturbing and distracting.

• 22:55Gary O'Reilly?

  It's like a really bad allergy you've got there.

• 23:01Gary O'Reilly?

  Okay, we've lost Chuck for a couple of minutes, I'll continue and sail on my own. All right, here we go professor. Give him his full name, Mark Erik Svensson. And his questions from Facebook. For obvious reasons, tennis serves and hits are faster with longer rackets. But at what point would the racket be too long? And the extra torque required would provide diminishing returns? So we've already had the larger head racket. So now it's gonna, you're gonna turn up with a Monty Python-esque giant tennis racket.

• 23:33Chuck Nice?

  Yeah. Where you play the game from the stands.

• 23:36Gary O'Reilly?

  Yeah, so what's the limit? Where, where, just how far shouldn't we go?

• 23:39Chuck Nice?

  Yeah.

• 23:40Speaker 02

  Well, the, the ITF, the International Tennis Federation rules set the limit at 29 inches. Typically, players are in the 27 to 27 and a half inch range. So that these rackets are about nine to 14 ounces. You know, so nearly a pound. I mean, the problem is, of course, if you, if you were to make it too long, now you're making the racket heavier. So you are going to be able to get more torque on it, but it's also going to cost you more energy to swing your racket. So you're gonna get tired faster.

• 24:13Gary O'Reilly?

  So someone like John Isner, who's what, six foot eight, six foot nine?

• 24:17Chuck Nice?

  Holy crap.

• 24:17Gary O'Reilly?

  Could you imagine giving him a regular sized tennis racket? It would look like a table tennis paddle. So he is going to have a naturally longer racket because he's got these naturally longer levers. So there must be some room for the bigger, taller players to be able to have longer rackets.

• 24:33Speaker 02

  Well, I mean, you know, taller players often have an advantage in a lot of sports. I mean, you say mold is tall, you get Randy Johnson throwing off of a pitching mound. You know, I mean, basketball players, obviously. So, you know, that, that added ability to increase torque with your just natural height or arm length, uh, it's just one of your gifts.

• 24:54Chuck Nice?

  And you cover more of the court just because you're natural tall.

• 24:57Gary O'Reilly?

  It's like a basketball player, you've got that wingspan.

• 25:00Chuck Nice?

  Right.

• 25:00Gary O'Reilly?

  So, you know, you're not having to shuttle across the baseline so much to get to a, to a shot that's in the corner. You just reach out that wing and pop, there it goes, back again, just arm strength.

• 25:12Chuck Nice?

  So is there a place where it can be too long? Because he talks about diminishing returns here. Is there a point where the length of the racket actually is a detriment?

• 25:23Speaker 02

  Well, again, it depends on the player. I mean, if you're an amateur, you don't want to be using, you know, the piece of equipment that's a little too big for you. If you're swinging something with more mass because it's longer, there's an energy cost to that. You know, every time you swing that racket, it's gonna consume calories in your body, so you're gonna have to take that into account, you know, if you're gonna be playing a five-set match over several hours.

• 25:49Gary O'Reilly?

  That's interesting. That's a whole nother different type of science then because it's conditioning, fitness, and muscle strength. All right, moving on to our next question. Samit Sina from Facebook in Barrington, Illinois. Many players choose to use shock absorber on their strings. They range in the size and shape, but all seem to function similarly. How are these small rubber-esque pieces able to reduce the shock felt while hitting the ball? And he goes on to ask, are there any performance benefits to using one aside from mere player preference?

• 26:23Chuck Nice?

  So first of all, you're gonna have to explain, what is a shock absorber? Is that the little rubber grommets that actually house the string at the rim of the racket?

• 26:34Gary O'Reilly?

  So on a racket, on the racket head, you will have a sweet spot. Then you'll have a point of percussion and somewhere along the line, and then sort of the balance and everything. But let the professor explain rather than me, because he is the professor, and obviously I am not.

• 26:49Speaker 02

  So if you put some mass on the racket, you know, just little bead or anything, just any kind of mass on a string, if it's vibrating and you've put mass on it, then the vibration's gonna dampen much faster. There's more inertia, there's more mass you're trying to swing back and forth. But what the shock absorbers, or those little grommets, really do is they get rid of the ping. So when you hit the tennis ball with the racket, the string vibrations are kind of in the 500 to 600 hertz range. So we can hear those as like a ping. If you put the little grommet on there, the little shock absorber, that tends to deaden the hit and it sounds more like a thud.

• 27:33Speaker 02

  But it's not going to help you with the vibrational energy in the racket because most of that's actually in the frame.

• 27:38Chuck Nice?

  Mm-hmm.

• 27:39Speaker 02

  And the reason is the frame is about 20 times more massive than the strings. So what's really dampening out the energy in the racket is your hand.

• 27:48Chuck Nice?

  Ah-ha.

• 27:49Speaker 02

  It's not, the little grommets are more for the sound than anything else. It's not really going to save your hand much.

• 27:56Gary O'Reilly?

  Will those little shock absorbers affect the sweet spot? I know the size of the racket head has increased the size of the sweet spot and players love that, but does it have any effect in that sense?

• 28:06Speaker 02

  Almost none.

• 28:07Gary O'Reilly?

  Or that much?

• 28:09Speaker 02

  Yeah, almost none. You don't get a real change in where the sweet spot is with that.

• 28:13Chuck Nice?

  So then really, to dampen the vibration of the racket during these, you know, high-intensity collisions with the ball, you really would have to have some kind of material, like a tempered foam or something like that, on the grip. Or what would you do to reduce that is really what I'm asking.

• 28:36Speaker 02

  So if you hit it in the, I mean, there are technically two sweet spots. I mean, there's a vibrational node and then a little bit closer to the throat is the center of percussion. Now, one of the vibration node is where if you hit the ball there, you don't get any vibrations. You get a little bit of a shock in the hand if you hit it at the center of percussion. And they're not too far apart, so these spots are very close together. But you get a small vibration and if you hit it at the center of percussion, but you don't get any shock in the hand. So that big, you know, spot in the middle of the racket where you're trying to hit the ball is going to keep the vibrations low on the hand. Now, the power point is much closer to the throat, more the center of the racket, so

• 29:21Speaker 02

  it's kind of down on the strings, away from the tip in the throat of the string bed. Now, that'll have significant vibrations. You're really going to feel that, even if you get a lot more power from your shot.

• 29:33Chuck Nice?

  Wow. And so are players cognizant of this? When you're a professional player, are you actually looking at a ball and making the mental calculation, even though this ball may be coming at you at 100-plus miles per hour? Are you actually making a hand-eye 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 want to hit the ball on that racket. I mean, this is a piece of equipment that's in their hand for, you know, hours a day, practicing for years and years. So they have a very, very good feel for where that ball's going to hit the racket when they're swinging it.

• 30:18Gary O'Reilly?

  If I relate that to my playing days in soccer, you know that to execute a certain pass, a certain shot requires a certain skill. Now, if it's a cross-court volley, if it's a slyce, if it's a topspin return, and I need to place that ball directly in the tram lines on that far side if I'm playing doubles or just in that corner, because now, two shots later, I'm going to kill my opponent.

• 30:42Chuck Nice?

  Right.

• 30:42Gary O'Reilly?

  I have to be able to dial up a certain series of shots and the techniques that are in there that I will have, as the professor says, 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 it. The calculation through my brain to my body through history.

• 31:02Chuck Nice?

  Right.

• 31:03Gary O'Reilly?

  Is there. And that's what you're seeing. These guys are so practiced.

• 31:06Chuck Nice?

  It's a programmed, it's a programmed reaction.

• 31:07Gary O'Reilly?

  Yeah.

• 31:08Chuck Nice?

  Is what it is through, through, um, experience.

• 31:11Gary O'Reilly?

  Then I get to the point where my opponent knows I'm going to dial up this shot.

• 31:15Chuck Nice?

  Right.

• 31:16Gary O'Reilly?

  So I just throw the eyes.

• 31:19Chuck Nice?

  Right.

• 31:19Gary O'Reilly?

  So I'm now looking at that far corner, and then I'll just cut it to the other side. And he will follow my eyes, or I...

• 31:26Chuck Nice?

  Right, because he's anticipating what you're anticipating.

• 31:28Gary O'Reilly?

  Absolutely. So now, now you get to the real genius.

• 31:30Chuck Nice?

  Exactly.

• 31:30Gary O'Reilly?

  These guys are calculating that you're calculating and calculating against your calculation, and it just gets better and better and better.

• 31:37Chuck Nice?

  And you know what? What you just 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, in tennis, it's like when you see a cross-court, cross-court shot, and then you see the return, which should be back across the court.

• 31:57Gary O'Reilly?

  Yeah.

• 31:57Chuck Nice?

  But it goes straight down the line. And it's, and you see the, the guy who made the cross-court is just like, damn, he got me.

• 32:03Gary O'Reilly?

  Yeah.

• 32:04Chuck Nice?

  He totally got me. And the same thing in football, where you hear linebackers talk about watching the quarterback's eyes.

• 32:11Gary O'Reilly?

  Oh, yeah.

• 32:12Chuck Nice?

  Like, how good do you have to be to be on a level where you're playing this sport and reading somebody's eyes at the same, I mean, it's, it's incredible.

• 32:23Gary O'Reilly?

  They won't just read the eyes. They will now read the body language because... If they're really that sharply in tune mentally, they will know the potential is to go down the line or across. So now the eyes are one read, that's one tell. The other one is body language.

• 32:40Chuck Nice?

  Because you're seeing the setup for the shot.

• 32:43Gary O'Reilly?

  I have to put my body in a certain shape to play a certain shot. So therefore, they immediately calculate what's wrong with this picture. And that's how I said, the levels get better and better. And as a spectator, when you see Nadal, when you see Federer, when you see Murray, when you see Djokovic, you are watching guys that are so good at every single category.

• 33:02Chuck Nice?

  Absolutely.

• 33:03Speaker 02

  Well, and two quick points. Even the best of the best, you're going to see faults, unforced errors. I mean, you know, they're not going to be able to hit it exactly the way they want it every single time. And the second point is, there's research that's shown the eyes cannot follow a pitched baseball, you know, that four tenths of a second that it's traveling. So it's the same thing with a fast moving tennis ball. I mean, they're not able to actually track the ball every little millimeter of its trajectory. I mean, there's enough intuitive physics, you know, the biomechanics that they've trained themselves for years to know where to be, where to, you know, react to a certain, you know, even sound of the ball coming off the racket.

• 33:46Gary O'Reilly?

  That's a fabulous point, Professor, because now it becomes a sensual thing. You're looking, and you're hearing, and you're looking at eyes, you're looking at body shape, you're looking at noises, and all sorts of different things. And all of a sudden, when the noise of the racket is another tell. It's like, remember you said, you're off again.

• 34:04Chuck Nice?

  It's very sensual.

• 34:05Gary O'Reilly?

  You know, that thud on a homerun.

• 34:08Chuck Nice?

  Right.

• 34:09Gary O'Reilly?

  Where you just go, head up, this one's leaving the park.

• 34:11Chuck Nice?

  Yeah, that crack.

• 34:12Gary O'Reilly?

  You know that. You know that. The same with the tennis. And that's how, that's how high level these players are. It's fabulous.

• 34:18Chuck Nice?

  Yeah, well, it's a game of inches and grunting and balls. And gosh, it is very, very sensual.

• 34:26Gary O'Reilly?

  We are going to take another break. If we didn't get, I think, just mainly for Chuck's benefit, I'm gonna shower. If we haven't got to your questions, I do apologize. We are limited in the time because, once again, big thanks to everybody. We've got so many questions in. We do our best to cover as many as possible. We are going to take that break. The good professor, Professor Eric Goff, author of Gold Medal of Physics, will be staying with us. So will you. I hope that break now. We'll be back very, very shortly, where we'll touch on courts and surfaces. So if your question was in that category, stick around. You're up next.

• 35:03Gary O'Reilly?

  We're back, yes, playing with science. Cosmic Queer is the tennis special, built by our own listeners. So we have a big thank out to every single one of you who threw your questions in. Hopefully, we've pulled them out of the hat. So we've got the professor, Eric Goff, with us still. So we will have him unlock the answers in all of your questions. So, right, courts, surfaces, and more. So Chuck, next question, please.

• 35:33Chuck Nice?

  Yeah, this is Joe Gassior from Facebook, and he's from Barrington, Illinois.

• 35:38Gary O'Reilly?

  Oh, second from Barrington, Illinois.

• 35:40Speaker 02

  Yeah, number two.

• 35:41Chuck Nice?

  Yeah, Joe wants to know this. How do players slide on different surfaces, clay, grass, hard courts? Is there a different technique 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, too, are they using different footwear for these different surfaces? I mean, that...

• 36:04Gary O'Reilly?

  I would say yes, but I'm gonna go with the professor's answer.

• 36:08Chuck Nice?

  But go ahead, professor.

• 36:09Speaker 02

  Well, so, grass is certainly the fastest surface. The grass is a little slicker. You get a little less friction on the ball. The bounces aren't quite as high. When you're seeing a match on grass, the players tend to be using a lot more speed and power. The rallies don't last quite as long. If you're a big, powerful server, you're gonna love grass. The hard courts usually have some kind of synthetic or acrylic layer sitting on an asphalt or concrete base. Those are...

• 36:43Speaker 02

  Kind of 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 and the players use a lot of topspin and sliding on clay. You have all the particulates down on the surface so the shoes are able to slide a lot better on the clay. Although a facet of my new research that was just published is we're seeing a rea- uh, we've now got a pretty good explanation for why you're seeing sliding more on hard courts.

• 37:14Gary O'Reilly?

  Oh, come on then. Drum roll, drum roll. New research.

• 37:20Speaker 02

  Uh, this was, this was work I did a year spin at the University of Sheffield. So any of our UK listeners, check out Matt Carey at the University of Sheffield. And anyone in the US who's looking to do some sports science, uh, check me out here at Lynchburg College. And what we're doing right now is we're looking into shoe treads and what we found by studying some rubber with holes in it is if you make these little dimpled holes, there's a critical area, a critical ratio of the area of the holes to the total contact area. And if you go past it, the static friction drops by more than 11% on

• 38:00Speaker 02

  a hard court. So what that means is if you're, if you put your shoe down and it's not quite sliding, the static friction is what you feel. Once it starts to slide, we call that kinetic friction. But if you can reduce that static friction, you can initiate sliding much faster.

• 38:18Gary O'Reilly?

  So basically like a, a race car tire. So you, you have different grades. So you go from slicks to medium to wet weather tires and as accordingly. But it's interesting with the, the holes in the rubber. What size of holes are we talking about here? Cause-

• 38:33Speaker 02

  So if you can get something of order 25% of a contact area of the shoe to have kind of a dimple or a hold area, you're going to get a reduction in this, uh, slide friction, you know, to initiate the slide quicker. Uh, if you look at Roger Federer, he uses a Nike court zoom. You'll see exaggerated and deeper cut herringbone on the outside of the shoe. Novak Djokovic, who's really one of the pros that makes a lot of use of sliding.

• 39:05Gary O'Reilly?

  Yeah, he's an incredibly athletic player.

• 39:07Speaker 02

  Absolutely. I mean, he's got an Adidas Novak Pro named after him. You'll see these, a deep grooved circular section on the outside of his shoe. Andy Murray, you know, from Gary's neck of the woods. I mean, he's gonna have a.

• 39:21Gary O'Reilly?

  Well, he's left Adidas and gone to Under Armour, hasn't he?

• 39:24Speaker 02

  He's got an Under Armour Charged Ultimate and you'll notice it's got like four cutout sections on the outside edge. So again, the gaps are gonna help him slide. Even younger players like Diego Schwartzman uses a Fila Cage Delirium and it's quite different from the other.

• 39:40Gary O'Reilly?

  That's actually a shoe, right? Because that's.

• 39:42Chuck Nice?

  Yeah, because it actually sounds like a very dangerous dog.

• 39:46Gary O'Reilly?

  Yeah.

• 39:47Chuck Nice?

  The Fila Cage Delirium.

• 39:49Speaker 02

  Yeah, very.

• 39:50Gary O'Reilly?

  It sounds slightly cyborg, yeah. It's interesting, when you talked about holes in the soles of the shoe, because Adidas made a shoe for soccer, but a flat shoe, not a studded or cleated shoe, back in the 60s, and it had sort of suction cups throughout the sole. And when you sort of talked about holes, but you're not talking about that sort of thing, it's actually the opposite.

• 40:18Speaker 02

  Yeah, these are, I mean, we're talking about like dimples, not dimples. So you're talking about grooves or some kind of depressions into the rubber, into the sole of the shoe. And the idea is, is that it will start sliding if you have enough hole area to initiate this slide. You can go out and buy a Wilson Glide shoe and it's got these two slide plates in each of the shoes and you can kind of get practiced on sliding with that. But all of these shoes that the pros are using on the hard courts, the ones that are taking advantage of sliding, you're gonna notice some gaps in the tread that get a little wider than some of the traditional herringbone patterns.

• 41:01Chuck Nice?

  So it's really, it's really shoe technology that it's brought this about.

• 41:04Speaker 02

  Oh yeah, I mean it's changing the game on hard courts because sliding used to be really the purview of clay and to some extent on grass too, but I mean really clay was the, you know, the sliding surface, but once you start adding in something new like sliding on hardcore, I mean, you're changing the shots that the elite are going to be able to reach.

• 41:26Gary O'Reilly?

  This will have been driven by the players because the players' style has said, "Look, I can't have an aggressive tread on the sole of my shoe because it's impeding the style of game that I bring." So they'll have gone back to their manufacturer and said, "Can you construct something that allows me to do this?" The only thing I'm thinking now is if you start to slide on a hardcore, that sole better be fire retardant because you're gonna get really, really hot shoes. And that's another thing because all of a sudden your feet burn and you will get the destruction on your skin. I mean, from playing on hard surfaces as a soccer player, you will get a lot of friction and that gets, that energy

• 42:10Gary O'Reilly?

  gets transmitted up through the shoe into the foot.

• 42:13Chuck Nice?

  Okay, well, in that case, I'm all for it because nothing would make me happier than to be at a professional tennis match and see somebody's...

• 42:19Gary O'Reilly?

  And see combusted fire.

• 42:20Chuck Nice?

  That's right. See somebody's feet burst into flame? Oh, God.

• 42:23Speaker 02

  I think that's why they also swap shoes out sometimes too.

• 42:28Gary O'Reilly?

  Yeah, it's a whole new meaning to this "players on fire."

• 42:31Chuck Nice?

  Hot foot, baby. All right. Okay, so now Julian Jans from Facebook wants to know this. If we make a tennis field with moon dust, will it have the effect, uh, that, will it have the effect than Roland Garros tennis field? Uh, will the bounce be better or worse compared to other surfaces? Uh, what's a Roland Garros tennis field?

• 42:57Gary O'Reilly?

  Roland Garros was a famous French tennis player and Roland Garros is the number one tennis court and complex in France, in Paris, and it is where the French Open is played.

• 43:07Chuck Nice?

  It's where the French Open is. Okay. And so, uh, if you made it out of moon dust, will you get the same consistency as a clay court?

• 43:15Gary O'Reilly?

  Well, I think someone's gonna sort of come in late at night and steal it because we know how valuable moon dust is, but there's only one person to answer that. Professor? Moon dust? Tennis court? Where do we go from there?

• 43:27Speaker 02

  So, the majority of moon dust is, is a silicon dioxide glass and it's come about from a bunch of these meteorite collisions with the surface of the moon. But it's actually pretty nasty stuff. It's, uh, it's very abrasive. Um, some of the astronauts complained about it starting to get through their suits. Um, it also sticks to stuff. It'll stick to the, uh, the balls you're playing with, the shoes, the clothes, and the players wouldn't really want to breathe it in. It's got some iron in it. Uh, I mean, it's, it's not, not something you'd want to be playing tennis on.

• 44:04Chuck Nice?

  Okay.

• 44:05Gary O'Reilly?

  So it's a punishment. So if you've, if, if you're being punished, you've been sent to the moon dust court to play tennis.

• 44:12Speaker 02

  Sure. Yeah. And if you're on the moon and, you know, the gravitational pull's about a sixth what it is here, you're going to get some pretty long shots. So you're going to need a big court too.

• 44:22Chuck Nice?

  Yeah.

• 44:23Gary O'Reilly?

  Oh, Professor, good segue. Well done, sir. Joe McKillop on Facebook, he's tied straight into this. Right. What's the biggest thing in the solar system from which a ball hit by the best tennis pro could achieve escape velocity? Love the show, Joe. Thank you so much and we love your question, Professor.

• 44:41Chuck Nice?

  Yeah, but, but now what's he mean by what's the biggest thing?

• 44:43Gary O'Reilly?

  We don't know who, who he or she.

• 44:44Chuck Nice?

  Uh, well, yeah, it's true.

• 44:46Speaker 02

  Well, I think I could, I could, I can answer that. So, you know, if you're going to escape Earth, I mean, not even accounting for air resistance. I mean, just to get off the gravitational tug of the earth, you're going to need about a 25,000 mile per hour launch. Uh, you're going to need something a little more just to get past the, the atmosphere. So the idea is can you find something small enough in the solar system that you could hit a, you know, nice, strong tennis serve and it could actually leave the object without ever coming back?

• 45:16Chuck Nice?

  Hmm hmm.

• 45:17Speaker 02

  And... I, you know, had to check what the world record is on a tennis serve and it's Australia's Sam Growth. This is 163.4 miles an hour in 2012.

• 45:30Chuck Nice?

  Wow. Say that again. That's incredible. 163 miles per hour on a tennis serve?

• 45:36Speaker 02

  Yeah. So let's just say we're not quite at that point. We're going to hit, you know, 150 miles an hour. The escape speed actually kind of scales, or 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 28,000 times, that ratio is about 28,000 times too big. So I actually found a moon of Saturn, Hyperion, that'll do the trick. If you serve a tennis ball 150 miles an hour, it will escape Hyperion. You know, Hyperion's one of these little chaotic tumbling moons of Saturn that it's

• 46:20Speaker 02

  only a couple hundred miles wide in one direction, maybe 120 some odd miles in another direction. And you can actually get the ball to leave that little moon of Saturn.

• 46:30Chuck Nice?

  So really, the answer is the smallest thing in the solar system where you can achieve escape velocity is Hyperion.

• 46:39Gary O'Reilly?

  So let's pack our bags and head for the Hyperion Country Club.

• 46:42Chuck Nice?

  There you go.

• 46:42Gary O'Reilly?

  Rack it into...

• 46:43Chuck Nice?

  Oh dear.

• 46:44Gary O'Reilly?

  Rack it in both clubs.

• 46:45Chuck Nice?

  We've lost another ball again.

• 46:47Speaker 02

  Well, you might be able to find it.

• 46:49Chuck Nice?

  Down that escape velocity.

• 46:53Gary O'Reilly?

  Yeah, all of a sudden you'll find a whole lot of tennis balls in orbit around Saturn.

• 46:56Chuck Nice?

  Another lovely day here at the Hyperion Tennis Club where we're out of balls because we keep losing them to escape velocity. Oh, well. Anyway.

• 47:08Gary O'Reilly?

  We'll have to put the membership up.

• 47:11Chuck Nice?

  All right, let's move on.

• 47:12Gary O'Reilly?

  All right, next question.

• 47:13Chuck Nice?

  That was actually a very fascinating question, Joe. Thank you so much.

• 47:15Gary O'Reilly?

  Yes.

• 47:16Chuck Nice?

  This is Mr. G, and he comes to us through Twitter, at @DiatonicSciNerd. 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 gen tennis, anyone?

• 47:38Chuck Nice?

  Oh, Mr. G, you're so terribly clever. That's actually a really fun little thought experiment. Let's get some guys into space suits. Let's put them in a vacuum. And then let's play some tennis. What are we gonna look at? What kind of game are we looking at at that point? You know, we do know now that from our first segment that there's a lot of dynamics that we'll lose when it comes to the fuzziness of the ball. But what are we looking at, Professor?

• 48:08Speaker 02

  Well, you're also gonna lose sound, because you're not gonna have sound propagating in a vacuum.

• 48:13Chuck Nice?

  Ah, man, so that means I can't listen to all those wonderful grunts of people birthing pineapples.

• 48:18Speaker 02

  Unless you've got like a, you know, a microphone inside the helmet and, you know, speakers or something in there that you can hear the other player.

• 48:27Gary O'Reilly?

  We're bringing the sound effects. We'll make it work.

• 48:30Speaker 02

  So air resistance is obviously gone, so the balls are gonna be moving a lot faster. You're not gonna be able to get any effect from spin.

• 48:39Gary O'Reilly?

  Yes.

• 48:40Speaker 02

  You're not gonna have any air to whip around that ball and have that nice Magnus effect help curve the ball. So forget all those nice curves on your shots.

• 48:51Chuck Nice?

  So the result will be a really boring game of tennis, is basically what we're saying here.

• 48:57Speaker 02

  I mean, if you could serve 150 miles an hour, I mean, 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 game.

• 49:10Gary O'Reilly?

  Do you think vacuumed tennis is going to catch on?

• 49:13Speaker 02

  Well, think about the ball moving a lot faster and your ability to get to it wearing a big suit.

• 49:20Chuck Nice?

  Yeah, like I said, it's a really boring game of tennis. You serve, basically, everybody just holds serve. You serve and the other person watches the ball go by. That's the way the game is played.

• 49:30Gary O'Reilly?

  Hit, walk, hit, walk.

• 49:31Chuck Nice?

  Hit, walk, hit, walk, hit, walk, hit, walk. Okay.

• 49:34Gary O'Reilly?

  All right. Time for one more question.

• 49:36Chuck Nice?

  Just one more.

• 49:36Gary O'Reilly?

  Just the one more. Kevin Moynihan, go on then, Chuck.

• 49:39Chuck Nice?

  Kevin Moynihan wants to know this, coming to us from Facebook, and you have to answer this, Professor.

• 49:45Gary O'Reilly?

  Scientifically.

• 49:46Chuck Nice?

  Scientifically. Kevin says this, "How come I can't stop laughing at that picture of Trump playing tennis?"

• 49:54Speaker 02

  Probably because it's as funny as a picture of Trump playing president.

• 49:58Chuck Nice?

  Oh.

• 49:59Gary O'Reilly?

  Da da da da da da.

• 50:01Chuck Nice?

  Snap.

• 50:02Speaker 02

  I didn't need two days to come up with that conclusion and I live an hour from Charlottesville.

• 50:09Chuck Nice?

  Oh my God, you were, I gotta tell you, kudos. That was, that was excellent, my friend.

• 50:14Gary O'Reilly?

  Professor's got, Professor's got the answers, as proven once again.

• 50:17Chuck Nice?

  Oh, man.

• 50:18Gary O'Reilly?

  Professor Eric Goff, the author of Gold Medal Physics, thank you so much for your time. Thank you for bringing us the, the answers to so many of our listeners' questions. Thank you to our listeners. This show does not exist without you and your questions have been brilliant. And hopefully the answers have been fulfilling. Chuck?

• 50:39Chuck Nice?

  What another great show. That's all I can say. Lot of fun. Professor, thank you. It's always informative and entertaining when you are on and.

• 50:47Speaker 02

  Yeah, glad to be on.

• 50:48Chuck Nice?

  Yeah, man.

• 50:49Speaker 02

  Have fun.

• 50:49Chuck Nice?

  I can't wait to hook up with you at the Hyperion Tennis Club. Dear.

• 50:57Speaker 02

  It's gonna be a long, long, long trip to get there.

• 50:59Chuck Nice?

  I was gonna say, yeah, that's, that's, that's, that's quite a ways, isn't it?

• 51:02Gary O'Reilly?

  Yeah, it's just not quite around the corner. Right, that's it for today's show. Hope you've enjoyed it. Hope you tune into Playing with Science in the future. We do look forward to your company. Until then, bye bye.