Science and Society used to share much of the same intellectual space. Only recently have they diverged to the degree that they seem diametrically opposed at times. The Exchange is our attempt to rekindle some of the dialogue that occurred between the two fields.
In this installment, we’ve brought together Major League Soccer/FC Dallas‘ Ema Twumasi and Washington University in St. Louis chemistry professor, Sophia Hayes.
Ema Twumasi, a professional soccer player, has played for FC Dallas, Austin Bold FC, and Oklahoma Energy FC. In 2021, he played in 23 matches, starting in 19, and played for a total of 1,703 minutes, with an 86.3% accurate pass percentage. Twumasi recorded an assist in a win over Austin FC and achieved a couple of clean sheets. He also played four regular season matches for FC Dallas in 2020 and two in 2019. In college, Twumasi played for Wake Forest University and scored 16 goals with 11 assists in two seasons. Before his professional career, Twumasi was part of the Right to Dream Academy in Ghana, along with other notable players.
In light of a breakout season in 2022, FC Dallas signed Twumasi to a new three-year contract with club options for the 2025 and 2026 seasons.
Sophia E. Hayes is a chemistry professor at Washington University in St. Louis, where her research group focuses on understanding the structure and properties of various inorganic systems, including optically and electronically active materials like semiconductors. Her research interests encompass optically-pumped and optically-detected NMR, quadrupolar NMR of clusters and thin films, and carbon capture, utilization and sequestration. Hayes emphasizes the importance of utilizing technical innovations to combat climate change. With a PhD in chemistry from the University of California, Santa Barbara, and a bachelor’s degree from the University of California, Berkeley, Hayes has received various awards, including an NSF CAREER Award (2003), an Alfred P Sloan Foundation Fellowship (2007), and the Regitze R Vold Memorial Prize in solid-state NMR (2009).
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Ema Twumasi: What if a soccer ball was filled with helium? Is there another gas that would provide interesting results? How would that impact shots with regards to spin, curve, trajectory, distance, etc.
Shopia Hayes: This is such a fun and interesting question. I wish I had a more entertaining answer … When we think of helium balloons, they’re almost magical, aren’t they? They’re these beautiful orbs that float gently into the sky – the physics of that is that the helium gas is lighter than air and provides “lift”.
You’ve probably seen a small party balloon – with a diameter of about 30 cm (about 12 inches) — and filled with helium, that can lift just a little bit of weight (mass) – here for a balloon that’s about 8 grams.
But a soccer ball is tough and made of leather! It has a mass 50 times more than a balloon! (the actual value is close to 400 grams) So even with helium filling it, sadly, there would be just a tiny, tiny bit of lift. Filling with helium or air … it would behave nearly the same and the difference would be almost undetectable – barely any cool spin, curve, trajectory or distance effects – I’m sorry to say.
But let’s think about this … If you think about a hot air balloon, that is a VERY large volume, and it can even carry a basket with people … a very large mass (weight). These balloon that can carry weight like that are very large ( diameters of about 55 feet across, or 17 meters).
So how big would a soccer ball have to be to achieve that kind of lift – to see all the cool effects you are proposing?
That 400 gram soccer ball would need about 400 liters of helium gas. (A party balloon is only about 14 liters.) … that’s a soccer ball that would have to be about 91 cm in diameter … let’s call it a 1 meter diameter soccer ball, to get that kind of lift.
(I’d like to be that goalie, playing with a 1 meter ball—going into a 2.4 meter high goal!)
Sophia Hayes: How do you train for each one of these, to impart each one of those effects to the ball?
Ema Twumasi: Many repetitions and drills, it just feels natural to me at this point over the years. We sometimes also can also place objects or teammates in the ball’s flight path to ensure the correct curve/trajectory is being reached.”
Sophia Hayes: For example, I’m guessing that spin affects the trajectory and the curving path of the ball? How do you develop and practice those skills?
Ema Twumasi: The curving path is most impacted by how you strike the ball with what area of your foot.
If you want to kick the ball as straight as possible, you’re going to use the top-part of your foot to minimize the ball’s curve in the air.
If you’re trying to curve the ball and see that arch in the air, you need to use a different part of your foot, like the big toe for example. That is going to cause the ball’s spin rate and path the ball travels through the air to be a lot different. With the inside part of your foot, you can generate a higher spin rate which leads to more curve distance traveled.
You can also use the outside part of your foot instead of the inside, which will produce a similar effect, but curve in the opposite direction.
I develop and practice these skills by kicking the ball around with teammates and experimenting with different techniques. A lot of times we’re just messing around after practice when we work on trick shots.
Sophia Hayes: And is there an opportunity to redesign soccer balls with those in mind?
Ema Twumasi: I have no idea! If someone wants to send me a helium soccer ball, I’ll be happy to kick it around and find out but I’m not sure how that could be done.
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