Guest post by John Eric Goff, Ph.D.
I take a slight risk with this blog post’s title because the one question I’m most often asked by someone in the media is: aren’t you taking something away from a great athletic moment by subjecting it to scientific analysis? My full-throated response is, “Absolutely not!” Viewing the sports world through the lens of physics has not only deepened my understanding of how the universe works, it has made me appreciate how special today’s elite athletes are. A little understanding of the science behind what you are watching in Sochi right now only enhances your viewing experience.
Were you as thrilled as I was watching Sage Kotsenburg in his gold-medal performance in men’s slopestyle? I loved seeing the jaw on one of my daughters literally drop while she watched him spinning and twisting as he soared through the air. What about Jamie Anderson? She dominated slopestyle on the women’s side, and I would be shocked if you didn’t feel chills up your spine while watching her.
Don’t worry, I didn’t pick my daughter’s jaw off the floor and inundate her with lots of equations. But she did think it was neat when I pointed out during a replay how, when Kotsenburg was in the air and turned his arms a certain way, the rest of his body had to react by turning a different way. My daughter never heard me utter the phrase “angular momentum conservation,” but I couldn’t keep the thought out of my head that the same physics law that explains the complicated twists and turns of Kotsenburg’s and Anderson’s bodies while they are in the air is the same law that helps us understand the workings of atoms and the movements of galaxies.
The laws of physics put constraints on everything that happens; there is no way to get around them. In Winter Olympics events like skiing, luge, skeleton, bobsleigh, and ski jump, athletes are taken to high elevation with the express purpose of doing something amazing on their way to low elevation. They have a certain amount of gravitational potential energy at their starting points that exceeds what they’ll have at the finish lines. Energy is conserved, meaning it cannot be created or destroyed. It can, however, be transformed. Athletes at the top of a hill convert potential energy as efficiently as they can to kinetic energy, which translates into fast speeds down the hill. They lose energy to air resistance and friction with snow or ice, but they’ve become skilled at keeping losses near theoretical minima.
For example, consider the ski jump, where female Olympians are competing for the first time. Every competitor starts at the same point, i.e. the same elevation. They all want to make the jump and leave the snowy Earth with as much speed as possible. Watch how ski jumpers orient themselves on the way toward the jump as they try to maximize the transfer of potential energy to kinetic energy. They reduce air resistance by keeping their bodies bent and arms back so as to reduce air drag. Once in the air, they assume the famous “V” position, whereby their skies are together at the back and open toward the front at an angle around 25°-30°. Skintight body suits help reduce drag, and the “V” style enhances lift. Wind-tunnel and other types of testing have shown that lift increases about 30% when ski jumpers use the “V” style compared to the old way of keeping skies together and straight out: some birds have even evolved to spread their feathers in a “V” shape while in flight so as to increase lift. Ski jumpers must be incredibly flexible because they are nearly bent all the way over toward the front of their skies.
That athletes continue to set world records and do things never seen before is thanks, in part, to science. Materials science advances in equipment have been extraordinary. Polymers on fiberglass skis reduce friction; computer models assist luge and skeleton athletes, who hit speeds near 90 miles per hour while experiencing 5 gees around turns; and biomechanical studies have guided speed skaters as they average low 30’s mph, tops for self-propelled human effort.
Give science a chance to boost your Olympic enjoyment!
John Eric Goff is s a professor of physics and chair of the physics department at Lynchburg College. He is author of Gold Medal Physics: The Science of Sports, published by Johns Hopkins. He spoke recently with The Take Away about Olympic curling and speed skating. To read his blog, click here.