Seeing the Olympics through the eyes of a physicist

By John Eric Goff

Ponder for a moment how differently we all view the world.  All the lovely vibrations that tickle our eyes and ears are processed by a brain unique to each of us, a brain forged from genetic and environmental influences.  The following story, which I tell in the first chapter of my book, brought this idea home for me.

     My wife and I enjoyed a fortnight-long honeymoon in Japan.  That trip halfway around the world represented my first time outside the US.  Knowing no Japanese, I couldn’t read signs, and I often couldn’t tell whether we passed a restaurant or a gift shop on the street.  My wife, conversely, had lived in Japan for five years and is fluent in Japanese.  She moved effortlessly through the streets and subways.  We saw the same signs, but her brain processed the information in ways well beyond what my brain could do.  Suffice to note, we experienced the world in vastly different ways while traipsing through Shibuya, the Times Square of Japan.

     Not long after returning from Japan, my wife and I attended a baseball game in Cleveland’s Jacobs Field (now Progressive Field).  While sitting in the right-field bleachers, my wife noticed that she could see the ball coming off the bat before she heard the crack of the hit.  As a physicist well familiar with such phenomena because of working with the difference between light and sound speeds in my profession, I took no special notice.  What confused my wife was as utterly obvious to me as those signs in Japan were to her.

I’m sure that you can think of similar situations you’ve been in where you either understood more or less about something than someone else.  Some may say that ignorance is bliss, but I believe that the better we’ve trained our minds to experience the richness the world has to offer, the more joyfully we experience it.  The London Olympics are upon us, and I want to offer a glimpse at how I, as a physicist, see a few of the sporting events.

Start with the men’s 100-m dash, the winner of which will be called the “fastest man alive.”  My bold prediction is that this year’s winner will be Jamaican with an “A” in his first name and an “L” in his last name.  How’s that for a prediction?!?  Compare Usain Bolt at 6’ 5” tall and Asafa Powell at 6’ 3” to fellow Jamaican Yohan Blake at 5’ 11”.  Science tells us that longer-limbed individuals reach greater speeds than those with short limbs, but the latter group is capable of greater acceleration.  Look for Blake to get the early lead with his enhanced acceleration, but look for either Bolt or Powell to win the race with greater top speed.

For the women’s high jump, consider Blanka Vlašić from Croatia.  At 6’ 4” tall, she has an advantage over her shorter competitors in that her center of mass begins at a point higher than theirs.  She executes a perfect Fosbury Flop when she crosses over the bar, meaning that her center of mass actually passes under the bar.  Angular momentum conservation helps us understand that the rotation she initiated when she leapt off the ground is what allows her to rotate over the bar.

A shorter high-jumper, like Jesse Williams of the US, who is just a hair over 6’ tall, relies on his greater ability to accelerate as he approaches the jump.  His center of mass starts off lower than his taller competitors, but that disadvantage is compensated for by his greater launch speed.

My pick for the gold in the men’s +105-kg (231-lb) weightlifting snatch event is Behdad Salimi of Iran.  Salimi set the world record last year when he lifted 214 kg (472 lbs) about 7 feet off the floor in a time of roughly 3 seconds.  When I saw Salimi do that, I calculated that his energy output came to roughly 1 Calorie.  Estimating body efficiency at about 25%, that means that he burned about 4 Calories in lifting that weight.  You may simply see a big guy lifting a lot of weight.  I see someone burning the chemical energy content in a can of Diet Coke!  I also see someone exerting 2 hp (1.5 kW) of power during that 3-second lift.  That’s more than the power of a microwave oven and roughly the power of sunlight on one square meter on Earth.

When Brit cyclist Victoria Pendleton set the Olympic record in the 200-m time trial at 10.963 s four years ago in Beijing, I calculated that she burned about 8 Calories and outputted power at the rate of 1 hp (0.77 kW).  That’s half of what Salimi outputs during his lift and it’s twice the energy.  In other words, I see two Diet Cokes when I watch Pendleton ride!

Watch out for Missy Franklin of the US on the 200-m backstroke.  At just 17 years old, she could be one of the darlings of the Olympics.  Like Michael Phelps, Franklin has a body built for swimming.  Most of us have wingspans about the same length as our heights.  Franklin (6’ 1.5” tall, 6’ 4” wingspan) and Phelps ( 6’ 4” tall, 6’ 7” wingspan) are built for speed in the water.  Couple long wingspans with big hands and feet (Franklin wears a size 13, Phelps a size 14), and you get someone with leverage advantages and the ability to shovel lots of water with each stroke.  Their long torsos are like boat hulls, which help them glide through the water.

As a scientist, I also look for unifying principles.  I mentioned angular momentum conservation earlier with the high jump.  We physicists use that powerful conservation law when studying the subatomic world, the motions of galaxies, and everything in between, including sports.  When Chen Ruolin of China takes off from the 10-m platform in women’s diving, the rules prevent her from initiating twists from the platform.  Watch as she throws her arms in various directions, which initiate her twisting motion, just as angular momentum conservation tell us.  When German Sonja Pfeilschifter competes in the the women’s 50-m rifle three positions event, know that the rifling (or interior grooves) in her 0.22-caliber rifle’s barrel causes bullets to spin, thus enhancing their stability, again, as angular momentum conservation tells us.  Watch what Mitchell Watt of Australia does while in flight during the long jump competition.  He will rotate his upper body forward by throwing his arms down and behind him, which, by angular momentum conservation, causes his lower body to rotate forward.  That helps him land about 1 m (3 ft) farther than if he landed in an upright position.  Note what Viktoria Komova looks like while swinging big circles on the uneven bars just before letting go for the dismount.  Her legs will be straight out upon release, then she’ll quickly pull arms and legs in to spin faster in a tight ball, before slowing the spin down by moving arms and legs back out.  Why does all that happen?  You guessed it – conservation of angular momentum!

On the non-human projectile side, keep an eye on The Albert, which is an Adidas Tango 12 Series soccer ball designed for the London Olympics.  The ball has 32 thermally-bonded triangles with a grip texture.  An improved woven carcass and new bladder hold air in and keep water out better than past balls.  I’ll be watching the flight of the ball, especially the “knuckleballs” (to steal a baseball term) or balls with very little spin.  Balls tend to deflect toward their rougher sides (think about a classic whiffle ball).  If air happens to be separated from the ball near seams on one side and near a smooth panel on the other side, the ball will get deflected in the direction where the seams are.  Of course, we’re likely to see some great “banana” kicks with spinning balls.  Watch for the balls to curve in the direction that the leading part of the ball is moving.  Lots of great physics on a soccer field (or “football pitch” as the Brits will say)!

My picks for Olympic gold in soccer:  US women and Brazilian men.

I could go on and on about a whole host of other goodies to watch out for when taking in the Olympics, but space won’t allow it.  Check out my blog (link in bio below) for sports physics commentary during the Olympics.  Learn a little of the physics of sports and you’ll find that your enjoyment while watching the games will skyrocket!

John Eric Goff is a professor of Physics at Lynchburg College in Lynchburg, Virginia.  He is the author of Gold Medal Physics:  The Science of Sports, which contains chapters on a few Olympic sports.  Follow Eric’s Olympics physics commentary on his blog.

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