Physics Phun with Phriends
I wanted to share the longer version of an article I published for my school newspaper – on Page 9 in the flipbook for the issue coming out tomorrow, February 2nd. Check it out on the website, too, to see all of our cool page designs and other articles!
For this in-depth article, I had the opportunity to examine the physics behind Olympic sports. I had a conversation with my AP Chemistry and Physics teachers, Mr. Panzilius and Mr. Sumida, about the three disparate sports of skating, snowboarding and curling and compiled it into an article highlighting the common forces at work in each sport. My biggest takeaways: Olympic-level athletes use the conservation of momentum to their advantage and strive to move as smoothly as possible, in order to preserve their speed and save energy. It is amazing to see how hard Olympic athletes train to make minute changes that ultimately, using the power of physics, allow for vast improvements in their performance.
Physics Phun with Phriends
Skating with Momentum
One of the most important elements of figure skating is elaborate spins. Skaters start with their arms held out at their sides and bring them in, spinning faster as they do so.
“When the skater moves their arms inward while turning their body, it’s like you on a merry-go-round moving toward the middle. As you move toward the middle, there’s less of the body spinning. Since there’s less spinning, it can spin faster,” AP Physics teacher Philip Sumida said, illustrating the principle of the conservation of angular momentum.
Snowboard halfpipe is an Olympic event where stars like Shaun White glide back and forth from one side of a halfpipe to the other, while performing tricks and gaining amplitude.
Sumida described how snowboarders performed difficult tricks like the frontside 1080 double cork. “What they do is build up as much momentum as they can. It is pretty intense. By keeping his center of mass constant, White uses his energy to increase his height, using muscle to put a torque on himself; what he wants to do is use all of his energy to lift up. He twirls around to conserve his angular momentum. If he can pull himself in, you can get really cool-looking fast turns. The hardest part is rotating around and keeping his center of mass in the same spot,” Sumida said.
“These Olympic athletes have crews of people telling them they need energy to turn a 100th of a second sooner, so they can get an extra inch higher. That’s what they practice, getting that extra inch, just enough to be able to clear [the next jump]. It’s pretty amazing. It’s really all about building extra energy and momentum. If you think about it, he’s just a big pendulum – a huge swing back and forth. When you use a swing, the place you want to pump is at the top. That’s when you want to throw your body back, and when you throw your feet back what you’re really doing is pushing your center of mass upward. The last thing you want to do is go side to side. When you do, you don’t go as high, because you use all your energy slipping. You’re trying to move yourself up because when you move yourself up you’ll fall further with more gravitational potential energy.”
Curling up with Curling
Curling is an unusual winter sport in that competitors push brooms back and forth on the ice in front of a sliding giant stone. The aim is to melt the ice and let it refreeze, a process called regelation, in a way that directs the stone towards the goals.
The process of regelation in curling can easily be seen any time one goes ice skating.
“The way that ice skates work is that, by increasing the pressure, you’re changing the state of matter, because you’re changing the environment. Water is denser [than ice] because of the intermolecular forces. So, if you add pressure to the solid ice, it actually is going to melt. When you’re standing on top of an ice skate and you are applying that pressure, you’re increasing the pressure so much that it’s melting the ice underneath. You are creating a layer of water and you’re sliding across the water,” AP Chemistry teacher Stefan Panzilius said.
In the same way, curlers melt the ice in front of their stone to allow it to slide.
“When [curlers] rub the ground like that, what they’re trying to do is to warm it enough, so it melts. Even ice has friction. As the stone [slides] through, what should happen is that it should slow down. What [curlers] do when they actually curl is they’re actually trying to make it so that the object in motion [the stone] remains in motion and they do this by reducing friction on the ice,” Sumida said.
Ice, even when formed with an ice resurfacer, does not have a smooth surface when it freezes. “The curlers are trying to make it so that when the ice melts, it re-freezes solid [and smooth]. They want as much forward momentum of the [stone] as possible, [which means creating a smooth surface with little friction],” Sumida said.