Sydni Dunn

Staff Reporter at The Chronicle of Higher Education

Meet the Physicist Who Can Tell You All About the New World Cup Ball

Full 06252014 brazuca

Image: The Adidas Brazuca (Adidas)

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John Eric Goff, a professor and chair of the physics department at Lynchburg College, is among the millions of fans tuning into the 2014 FIFA World Cup in Brazil this summer. But Goff, a renowned sports physicist, is paying attention to more than the scorelines or even the highlight-reel goals; his eyes are following the spin and drag of the ball.

The Adidas Brazuca, the soccer ball created for the World Cup, has held Goff’s attention since December, when he analyzed how it would perform at this year’s event. Goff’s findings, which were published in the Journal of Sports and Engineering and Technology in March, showed the Brazuca was a better ball than the Adidas Jabulani, which drew complaints from players at the 2010 World Cup.

He’s now the go-to scholar for information about the ball’s performance. Here’s the story of how Goff made a career out of his love for sports and physics.

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Growing up, baseball was my sport. I played it all the time, I collected the cards, I had team stats rattling around in my head. And at one time, I had serious thoughts of playing professional baseball.

But being good in your Little League and being ready for the majors fall into very different planes of excellence. I quickly realized that even if I gave it all I had, I probably wouldn’t have made it past Single-A ball. I didn’t have “it.”

So I turned my attention elsewhere: physics. I often joke that I’m one of the few people who chose to go into physics because something else was too hard.

Flash forward to today: I’ve combined my two passions. I’m now an expert in sports physics, and most recently, the go-to physicist for information about the Adidas Brazuca.

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My research turned to sports physics when I joined the faculty at Lynchburg College, in Va., in 2002. There’s no graduate program for physics, so all of our undergraduates have to perform research projects as part of the major requirement. Some of the best projects were sports-oriented.

One of my first students, for example, was interested in cycling, and completed a computational-physics project predicting the stage-winning times of the Tour de France. I liked the project so much that when he graduated, I asked him to collaborate with me on a full-scale version. We modeled the entire 2003 Tour de France and published a paper in the American Journal of Physics in 2004.

In many ways, this paper set the rest in motion. It gained quite a bit of attention, including from an editor at The Johns Hopkins University Press. The editor asked if I was interested in writing a book, and I accepted. Gold Medal Physics: The Science of Sports—which discusses the science involved in American football, soccer, cycling, skating, diving, long jumping, and other competitive sports—was published in 2010.

Since then I’ve continued to publish on all of these topics. I also teach 12 contact hours per semester. My latest undertaking was research on the Brazuca and how it compares to the Jabulani, the much-maligned ball of the 2010 World Cup, in South Africa.

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My involvement in the project began in early December, when Takeshi Asai, a colleague at the University of Tsukuba in Japan, asked me to collaborate with him in his research of the Brazuca. He had used a wind tunnel to study the both soccer balls, and asked me to review the data he collected. I did the data analysis, the trajectory analysis, and I wrote the paper we published earlier this year in the Journal of Sports Engineering and Technology.

In that paper, we concluded that the Brazuca would perform better than the Jabulani. The differences in performance we saw reside in the ball’s design.

Adidas has supplied balls for the World Cup since 1970, and up until 2002, the same type of ball was used. That ball is most like the traditional black-and-white ball we all played with as children. It’s made up of 32 panels—20 hexagons and 12 pentagons.

In 2006, Adidas moved away from that model and created the Teamgeist. That ball had 14 thermally-bonded panels. The Jabulani, which debuted in 2010, had eight panels. And the Brazuca has only six.

But when you reduce the number of panels, you run the risk of making the ball too smooth. If it’s too smooth, it’s susceptible to more air drag. (Think about the dimples on a golf ball: If it were totally smooth, it wouldn’t fly nearly as far.) So with the Jabulani and Brazuca, Adidas had to intentionally texture the ball’s surface with hundreds of tiny raised bumps.

The Jabulani, however, suffered with its seam design. It had a geometry on its surface that wasn’t very uniform, meaning it could get deflected left or right, depending on how the ball was turned. The erratic flight patterns and knuckling effect resulted in players widely denouncing the ball.

The topical design of the Brazuca is a huge step up. The panels are shaped like propellers, which adds to the seam length and makes it more stable. In fact, if you take a string and measure the seam lengths of each ball, the Brazuca’s seams are 68 percent longer. That additional roughness leads to a “drag crisis” at a lower speed, meaning most intermediate-speed and all high-speed kicks should be in the region where the drag coefficient is essentially uniform.

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From what I’ve seen so far, our predictions have been correct. The Brazuca is behaving much better than the Jabulani. (If you need proof, turn to Lionel Messi. His first goal was a thing of beauty.)

Seeing our work play out on the field has been rewarding. It’s also been nice to share that work with the public. Since our paper was published, I’ve been contacted by NPR and The Wall Street Journal, among other media outlets, to discuss the research.

This is exciting not because of the personal attention, but because I get to help people understand the science behind their favorite sports, and potentially even turn some students on to the study of sports physics.

So in the end, I’m not a star baseball player like I once dreamed. But I am helping get science on the sports pages.

Lessons I’ve learned along the way:

  • Don’t give up if your first paper doesn’t get picked up. Years ago, one of my research papers was denied by the American Journal of Physics because the reviewer said soccer wasn’t an appealing topic. Instead of giving up, I sent it elsewhere, and it was accepted.
  • Make friends across your discipline. Be sure to network with others in your field. I would have never worked on this particular Brazuca research had it not been for my colleague in Japan. I met him years ago at a conference in Massachusetts and maintained contact.
  • If you’re not at an R1 institution, don’t fret. You, too, can do good science. The resources may be harder to come by, but there’s a way to find what you need. Look to universities in the UK, for example.
  • Just as your students learn from you, you can learn from students. At a place like Lynchburg, you can take students with a lot of self-doubt and leave them firmly believing they can be scientists. It’s a powerful thing to see that change in someone’s life. It’s also powerful to have them open your eyes to new things. Some of my best research was inspired my students’ projects.

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