Do you love Soccer? Is Futbol part of your life? If so, we have an episode for you.
Student intern Taylor Raybould requested a show on the physics of the almost universally beloved sport. Our guest today is Dr. Andreas Riemann, the chair of the WWU physics department. Dr. Riemann teaches physics of sports course and has a great time talking to Taylor about the world of soccer/futbol.
Note: This episode has a bit of an audio issue. We hope it isn’t too distracting
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Speaker: Here we go!
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Gina: Welcome to Spark Science. Today, we are talking about the science of soccer or the physics of futbol. And I’m here with one of my students who works on the show, volunteers on the show, Taylor Raybould, how are you doing?
Taylor: I’m doing very well. How are you today Gina?
Gina: Pretty good. And this was your idea?
Gina: And we brought an expert in soccer, or futbol, I like to say that. He might not think that of himself, but I think he’s an expert–a colleague of mine who teaches physics and astronomy at Western Washington University, Andreas Riemann.
Andreas: Thanks for having me.
Gina: So, we bought you in because you actually teach a course at Western Washington University. And, can you tell us the title and tell us a little bit about the course and like how it came to be?
Andreas: Yes, so the title is physics of soccer. So, I call it soccer so the general student is not confused if I would call it futbol, that we talk about American Futebol, but we talk about European futbol (soccer). It’s actually a 100-level class that can be taken by any student, not just science students but any kind of major. The prerequisites are pretty minimal, just some basic math and we go from there.
Gina: So, like what was the cause of this class? Why did you want to teach a class about soccer?
Andreas: Futbol …
Gina: Futbol … African futbol.
Andreas: Yeah, we decided to have a class on physics applications. And different instructors do different topics in this class–what they like. We have a physics of music and a physics of color …
Andreas: … and light. And I thought, you know, physics of soccer would be fun because you can do some basic mechanics, but you can also go a little bit deeper into the more interesting part of soccer.
Gina: How long have you been playing soccer?
Andreas: So, I grew up in Germany, so basically for my whole childhood I was playing soccer everyday. After school there was our after-school activity. Soccer, in Germany, is the sport number one. All the other sports are just …
Gina: … hobbies …
Andreas: … hobbies … not very proper, exactly. Every child plays soccer and it’s what I did growing up. And then I played a little bit in college, like intramurals. When I came over he ere I played a little bit just for fun. I really enjoy it.
Gina: So that’s why you picked that topic.
Gina: So, let’s bring it to Taylor because you’ve been working on the show for a little while. And you are very interested in soccer.
Taylor: I am …
Gina: So let’s go a little into that story and why you really wanted to have a show on the science of soccer, the physics of futbol.
Taylor: Well, believe it or not, I actually used to hate soccer. Because, when I first played …
Taylor: … I first played soccer in kindergarten and it was my absolute least favorite because I couldn’t run and kick the ball at the same time.
Gina: You were 5 . . .
Taylor: I . . . yes. It was a long time ago. But, a few years ago I watched the 2014 World Cup and that sort of revived my love for the sport.
Gina: Wow, so you went from like 5 to in your late teens just hating soccer?
Gina: Okay, good to know, good to know. And now you’ve just done a complete 180 …
Taylor: … complete . . .
Gina: And we were actually working on a show and you had to take a break and like watch a part of a game, I remember. And what game was that?
Taylor: That was the Barcelona’s 6-1 win over Paris St. Germain in the champions league rounds to move on the quarterfinals.
Gina: And you were like yelling in the hall and stuff.
Taylor: I was. I was throwing my hat around every time they scored because Barcelona was coming back from a 4 – nil defeat in the first leg. And so, the fact that they managed to win on aggregate overall was incredible.
Gina: So, are you kind of like in the state of mind where you would want more U.S.-born people to kind of get more into soccer?
Gina … and more into futbol?
Taylor: Absolutely. It’s one of … it’s the beautiful game. It’s one of the most simple and exquisite sports that there is to offer around the world. And the fact that so many people are so interested in it, except for America, is really disheartening.
Gina: So, you want to do like a science show on soccer, but why is that? What made you go into school and like . . . what is your major? What did you want to study when you went into university?
Taylor: Originally, I was a physics major, as you know . . .
Taylor: . . . being one of your students.
Gina: Yes. [Both chuckle.]
Taylor: But, since then I have moved on to kinesiology. I’m a movement studies specialization of kinesiology, which really focuses on the biomechanics and the movement of sports and other things like that.
Gina: And for our listeners, we had another show on kinesiology–you can check that out–earlier in the season. But, so you’re interested . . . I think you had a lot of questions that you wanted to ask Dr. Riemann about . . . when you are looking at a soccer game, when you are seeing the passes, all these kind of things, you had these questions. So, I wanted to let you ask some of these questions for our guest here.
Taylor: I do! Alright, my first question, my most burning question is: When you see a really amazing kick or a corner kick or a free kick in soccer (futbol) how does the spin on the ball come about? What causes that amazing curve that people can do to the soccer ball?
Andreas: I agree, that’s one of the more exciting kicks in soccer. Let’s step back a little bit, maybe back to my physics of soccer class . . .
Andreas: As I sad, the prerequisites for students is pretty minimal. So, we are starting out with understanding the basic ideas: how a ball moves, you’ve heard about projectile motion where we just assume no wind, no drag, no friction, or anything like this. So, we start out with that and we can explain most of the motion pretty well.
Gina: Yeah, so when we’re talking about projectile motion we’re just talking about, hey, something is moving in the air, we throw it at some angle and it will make this arc motion and that’s what we’re talking about with projectile motion.
Andreas: Exactly, so it moves like a parabola or so.
Andreas: But then, the interesting part what you asked, Taylor, about was when the ball is giving spin. So, the player kicks the ball slightly off center and the ball starts to rotate. When the ball starts to rotate, depending on the speed of the ball in the air, the air can do two different things basically. It can be in what is called a turbulent flow where you have basically this turbulence around the ball of the air. It’s like turbulent little twirls, if you want, around the ball. That’s when the ball moves really of fast. And then, when the ball slows down there’s what is called a laminar flow, where the air just flows around the ball.
Gina: Cutting through the air verses interacting with things on each side . . . like knocking it around a bit?
Andreas: Yeah, yeah, basically. And the interesting part about this one is that other players don’t really know what to expect because the ball first goes in this straight path because its in this turbulent flow. And then suddenly it slows down enough and then it starts to curve.
One of the more famous kicks was from Roberto Carlos when Brazil played against France in … I don’t know . . . 2010-ish, or is, about. You can see he’s taking a free kick. And, in soccer you always put people in front of the goal to make a wall.
Gina. Right, can and they’re like always covering themselves.
Andreas: They always protect themselves. [chuckling.]
Gina: That’s just what I remember from that kick. I don’t know very much about soccer.
Andreas: So anyway, so the wall is there to protect one part of the goal.
Gina: You are making this wall, are you going to cover the right part of the goal, the left part of the goal, the center … is that what you’re talking about?
Andreas: Yeah, exactly. So, usually like 1/3rd of the goal is protected by the wall, the other 2/3rds hopefully by the goalie.
Gina: Right, hopefully …
Andreas: Hopefully . . . Anyways, so this ball is going by this wall and basically, everybody thinks it’s going far next to the goal. However then, after the ball passes the wall, suddenly it starts to rotate and basically curves very beautifully into the corner of the goal.
Gina: Wow! So I need to look up this video.
Andreas: You definitely need to. Just “Roberto Carlos” and “Brazil France.”
Gina: Okay, and they weren’t expecting that at all? They were not guarding that tiny, tiny bit because they didn’t think it would be able to like curve in.
Andreas: No, because the straight path was basically …
Gina: And so the faster the ball is going, the more prolonged this curve will happen, right? At which time the curve will happen, right? So like, the faster it’s going it will curve at the very end, right?
Andreas: That’s right.
Gina: Okay. And like the slower it goes, it’s going to start curving pretty early.
Gina: Got it.
Andreas: If you kick it slow, I think like a corner kick in general, you kick a little bit slower and then it starts to curve right away.
Taylor: You can actually score a goal from a corner kick. And it’s really incredible to see people bend it out and then straight back in.
Gina: Okay, what do we mean by corner kicks? Like, where do corner kicks exist on the field? There’s only 4 corners, right?
Gina: So, you’re pretty close to the goal and you’re like on the same line–same horizontal line. You’re telling me it curves all the way like a hemisphere, kind of, like a half of a circle all the way back in.
Andreas: Yeah, horizontally it curves.
Gina: Wow. When you said . . . let me bring you back to when you said you were growing up and you were saying that everyone played soccer. Was it mostly . . . I think I asked you this before and I don’t remember the answer. Was it mostly males, like boys that were playing the soccer, and girls? Or was it, like or was it just the boys that were playing the soccer.
Andreas: No, unfortunately in Germany it’s very common that only boys play soccer. There is girls and women’s soccer also. In Germany it’s pretty good, the U.S. is even better.
Andres: … but it’s not …
Gina: I mean, The reason I asked is because in the United States it’s almost more of a female sport, soccer, when we’re dealing with elementary school and high school and the teams. So, we’re going to take a quick break and we’ll come back to this idea of pop culture and society and soccer later. But, we want to come back and I’m going to let Taylor ask some more questions about physics of futbol.
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♪ Early late at night
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♪ There’s a world inside
♪ Where dreamers meet each other
Taylor: Hello and welcome back, I’m Taylor Raybould here with Dr. Riemann talking about the physics of futbol. And, I have a question for you. Can the altitude that you play at affect the way the ball travels through the air? As we mentioned earlier, that soccer is a global sport. And so, whether if you’re playing in Buenos Aires or in Death Valley, does that have an effect on how the ball travels?
Gina: God, I’m so proud of him, he’s like so prepared.
Andreas: Yeah, he is. They are good questions. Okay so, we are back to the question of pressure. So, at higher altitudes you have thinner air. So, first of all, the ball would go much farther because one big thing is the air resistance which influences the flight of the path and the distance.
Gina: Like how much further though? I’m thinking like, let’s talk about like Colorado, like Boulder, Colorado or something. Would they be like, “Hey, hey, hey,” like, “They only got that shot,” or, “This is going further only because we’re here”? I mean, how much further?
Andreas: That’s a good question. I think in a regular, like at sea level or so, a goalie can get the ball definitely over the halfway line, which would be about 50 meters (50 yards) about. I think at high allotted it can definitely go, probably, all the way almost to the penalty box or so. So, yeah, so definitely that has an influence. I mean, fortunately both teams have the same advantage.
Gina: That’s true. That’s true. Which makes me think of a question that Taylor had talked to us about earlier. Um, so go ahead Taylor, ask another, ask another question.
Taylor: Yeah, we mentioned something about the penalty box earlier. And my next question is actually about penalties and angles. So, imagine you’re taking a penalty kick from 12 yards away. And, you kick the ball slightly off center. How off center can you be before you are over the goal, before you miss your shot?
Andreas: Okay, over the goal … yeah. You know, surprisingly, in misses in penalty kicks or so, it’s very often that they go over the goal because they want to have it high up so the goalie cannot get it. To quantify your question with the angle is, if it’s like 12 yards …
Gina: You need velocity right, you know, how hard you’re kicking it or how fast it’s going to start with, right? Not just the angle.
Andreas: That’s right. So, I mean, there’s, I think Clint Dempsey sometimes kicks a penalty kick where he just waits out the goalie and let the goalie go into one of the two corners and then he just chips it in the middle really slightly in, so. There was the penalty kick, I think it was in a Barcelona game even …
Taylor: Umm, Neymar’s?
Andreas: Where the person who took the penalty just kicked it slightly forward and then somebody else …
Taylor: Oh, that was Lionel Messi who laid it off for Luis Suarez.
Andreas: Okay, yeah that was. So, another famous kick you can …
Gina: Okay, so that person didn’t move continually up, or he passed it to somebody?
Andreas: Oh no, he moved it forward, the ball, but just slightly. And then somebody else came running from outside the box where you have to wait and kicked it in. So, that’s unusual.
Gina: How is that okay to do?
Taylor: It’s okay as long as the kicker doesn’t go into the penalty box.
Gina: Oh! One more question Taylor, do you have any more?
Taylor: Oh, I’ve got two more.
Taylor: Um, my next one is how much force is in a kick. How much power is produced when you kick a ball? I think you said 30 meters per second or something like that.
Andreas: I think that was the speed of the ball, we started with the speed of the ball of 30 meters per second.
Gina: On, that’s so fast though.
Andreas: Yeah, I mean that’s like at the beginning, right? And then ..
Gina: I’m going to write this down.
Andreas: 30 meters per second you have as the speed. And what else do we need is kind of how long is the foot actually in contact with the ball?
Gina: Because we’re talking about impulse now, we’re talking about force times change in … change in time, right?
Andreas: That’s right. Yes. Exactly. So we have to, the mass of the ball we set about 1 pound or a half a kilogram (to be in metric units) …
Gina: To make math easy for us?
Andreas: Yeah. Exactly. Because we don’t have calculators.
Gina: Nope. How about we’ll do this for our listeners. We’re going to take a quick break. And we’re going to come back. We know the values, millisecond, velocity that we shoot it out is about 30 meters per second, mass is about a half a kilogram. And we’re going to come back with the power, right? That’s what you asked? The power of that kick.
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Gina: Welcome back to Spark Science. We just took a break from actually doing some calculations. We’re talking about Dr. Riemann and my student and show volunteer Taylor Raybould. And we were just talking about what is the power in a kick, was the question. And, two physics professors had to take a second to be like, “okay, how do we calculate that.” And what we decided was . . . we put together … energy per time is really what we’re talking about power. We’re talking about watts, which is joules per time.
We got roughly with 100th of a second being the contact of the kick, maybe the velocity of this initial ball after the kick is 30 meters per second, half a kilogram for the mass. We estimated roughly 25,000 watts. And that might not mean anything to anyone. But, if we convert that to horsepower that’s like 30 horsepower.
And I remember us talking a different time about like what is the horsepower of like a car, right? What did we say, it’s like . . .
Andreas: 200 horsepower.
Gina: 200? Yeah. So, it seems about reasonable that that would be the power produced in a kick.
Andreas: Right, just keep in mind that 30 horsepower are just over a very short amount of time. So, it’s not sustainable.
Gina: Right, that 100th of a second.
Gina: Well, we’ll come back to culture and [laughs] society later. But, I’m going to let Taylor, actually, ask the last like burning question that you had.
Taylor: My last burning question isn’t necessarily about physics, but it is for Dr. Riemann. Who do you think will win the World Cup in 2018?
Andreas: 2018, yeah, in Russia.
Andreas: So, you know we talked about this a while back. And I thought Germany has a chance. And then, in between there was a little tournament to warm up for the World Cup where the best teams from each continent kind of participated. And Germany actually won that tournament with kind of a junior team.
Gina: Oh wow. What is this . . . who is this junior team we speak of?
Andreas: You know, the big stars for Germany they stay at home. Either they were injured or they had a long season. So, Germany took their young players …
Gina: Oh got it, okay.
Andreas … 21 to 25 …
Gina: And they still won, is what you’re telling me.
Andreas: … and they won. They had a good tournament. The final was against Chile, which is also a really good team. I think they’re definitely also a contender for next year. Germany won. A little bit lucky, you know, but they won. So, I think they’re in the mix. Then, like I said Chile. Always Brazil. Argentina are always there. And some European powerhouses like Italy, Spain, France. And I think it’s the usual suspects plus Chile, I would say, for next year. So, what do you think Taylor?
Taylor: Well, I’m always going to be rooting for Argentina, which is my favorite national team. But, I’m going to say either Italy or France, I think will take home the gold.
Andreas: Okay, that’s possible. What about you Gina? What do you think?
Gina: [Laughing.] I have no allegiance to any soccer team. I just will do … I’ll just agree with whatever somebody knows more about. But, once I start watching the world cup, once …. you started having favorites. Like, you started seeing like, kind of the fan base and the craziness and … I’m just going have to watch and see which one I like the best.
But, I kind of want to ask the question to both of you, for soccer novices like me, who are the big teams in each continent. Because, the last conversation we had offline we were talking about common teams that go … kind of every year to . . . every 4 years to the World Cup. And we talked about north America, the dominant one being Mexico in North America. So you have 3 teams: Canada, United States, and Mexico. And even Canada isn’t very there almost ever, right, that’s what you said?
Andreas: Canada is even worse than the United States.
Gina: Yeah, exactly, so that made me feel better. And then, like you have South America. And you said Argentina is very big, Chile is very big. What about Africa, Asia, what are … what are . . . who are the big teams or big countries represented at the World Cup?
Taylor: In Asia, there’s not a lot of soccer base, and so ….
Gina: I thought like South Korea was better. Or is that just because the World Cup was there that year?
Andreas: I think, really, when the World Cup was there in Japan and South Korea, they had like kind of home … home team advantage, but they haven’t been doing very well the last couple of years.
Andreas: And then … you know the world is waiting for an African team to really step up. And they’re … every year like Ghana or Cameroon or there is always a team which is on the verge, but they haven’t made it really, you know, to a semifinal, I believe there hasn’t been an African country in the semifinals.
Gina: So, with my last question, which I end almost every episode of Spark Science this way, we talk about pop culture and how like science has been represented in pop culture. But, now that we’re talking about soccer, we can talk about how is soccer being represented in movies, TV. And also, has there ever been a movie or a tv show that you watched and you saw them playing soccer and you’re like, “Nah, that’s super” … one maybe it’s physically inaccurate and two maybe it’s just not the way the culture around soccer is.
Andreas: Yeah, soccer movies are no popular either.
Gina: Even in other countries where soccer is … like we’ve been talking about this thing where it is really a way of life. I’ve been told this by people at work. It’s really a way of life in other parts of the world, but not necessarily here in the United States. So, even in other countries there’s not like …
Andreas: No, somehow you don’t make a movie about that. It’s kind of …
Gina: It just is. It’s like making a movie about washing dishes.
Andreas: Yeah. [Both chuckle.] Basically, I think. Yeah, you just do it. You don’t make a movie about it. So, yeah. Bend it like Beckham, I guess, about cultural differences and girls playing soccer. I think that’s the only one I can think of to soccer references like …
Gina: But I think Taylor had brought up pop culture, not just movies, but video games
Taylor: [Speaks simultaneously with Gina.] Video games …
Taylor: Yeah [chuckles.] FIFA is one of the sort of biggest franchises that there is as far as video games go–like sports video games. And that has a big presence in the United States, unlike movies or TV shows or really soccer itself.
Gina: Yeah. And we were talking about how they put out a new one every year, right? Every year! And the world cup is every 4 years! Yet FIFA puts out this game every year.
Taylor: Yup, it updates the rosters, it updates all the players ….
Gina: That’s insane.
Taylor: … it has statistics for each player. And you can like create your own team, you can create your own league, and players and all that sort of stuff.
Gina: So, that’s super interesting. I learned a lot about kind of turbulence and thinking about these things. I mostly learned a lot about soccer rules. But, I want to thank Dr. Riemann for being here, Andreas. And I want to thank Taylor for these awesome … these awesome prepared questions. Thanks a lot for being here.
Andreas: Yeah, thanks for having me. It was fun.
Gina: This is Spark Science and we’ll be back again next week. Listen to us on 102.3 FM in Bellingham or KMRE.org. Streaming on Sundays at 5pm, Thursday at noon, and Saturdays at 3pm. If there’s a science idea you are curious about, send us an email or a post a message on our Facebook page: Spark Science. This is an all-volunteer run show so if you want to help us out, go to SparkScienceNow.com and click on “Donate.” Our producer is Regina Barbara DeGraf. The engineer for today’s show is Natalie Moore. Our theme music is Chemical Calisthenics by Blackalicious and Wondaland by Janelle Monae.
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