Ski racing is in her blood, physics on the mind of Aspen student Jane Marolt
Ski racing is in Jane Marolt’s bloodline, and the Aspen High School senior also happens to be talented in physics. As such, that got her thinking one day about the composition of speed suits.
Marolt came across a study that confirmed her suspicions that the slick material used in speed suits allows air to pass over it more fluidly by hugging a racer’s body and maximizing aerodynamics. So far, so good, she thought.
But counter-intuitively, Marolt also learned that speed suits have a high coefficient of friction, despite that slick feel. The suits are designed to slow a racer down when they take a tumble so they can scrub speed and reduce the force in case of a collision.
Marolt comes from a ski racing family. Her grandfather, the late Max Marolt, earned a place on the U.S. Ski Team in 1954. He raced in the 1960 Olympics in Squaw Valley, California. Her great uncle, Bill Marolt, was inducted into the U.S. Ski and Snowboard Hall of Fame in 1993. He had a career as a ski racer, coach of the University of Colorado ski team and coach of the U.S. Ski Team and later headed the U.S. Ski and Snowboard Association. Jane’s uncles, Steve and Mike Marolt, were selected last year for the U.S. Ski and Snowboard Hall of Fame and will be inducted in April, not for racing but mountaineering. Outside Magazine called them “two of the most accomplished ski mountaineers alive.”
Jane is herself a ski racer. She participates on the Aspen High School ski team. She got curious about how the coefficient of different types of speed suits would compare with one another as well as with regular ski wear. She initially reasoned that the kind of clothes recreational skiers wear feel much more coarse, so they must have a high coefficient of friction.
She decided to take on the physics experiment as her International Baccalaureate Diploma Program project.
“I think it was a really challenging experiment to conduct,” said her adviser, Aspen High School science teacher Marc Whitley.
Marolt decided to test the coefficient of friction of three different ages of Spyder giant slalom suits: a Spyder downhill suit, a Spyder training suit as well as a recreational ski pant by Aspen ski-wear manufacturer Obermeyer.
“At the time I had to do the experiment it hadn’t snowed yet, so I had to do it in my house,” Marolt said.
She rigged up an incline plane and created bundles of equal weight and surface area for each ski suit. She determined the angle of repose — the angle at which the materials started sliding — 10 times for each suit, then averaged them and calculated the coefficient of friction.
Unfortunately, she said, the lack of early-season snow severely limited her ability to expand the experiment outdoors. She took the garments to the ski hill and measured off 40 meters. She then timed how long it took her to slide the 40 meters while wearing the various garments. She verified the results from the indoor experiment — regular skiwear slides a lot more easily than the racing gear. The racing suits didn’t slide at all.
Marolt also interviewed a designer at Obermeyer to learn more about their philosophy. The top concerns are warmth, comfort and function. Their clothes aren’t targeted toward racers, so the coefficient of friction isn’t as high of a concern, she said.
Marolt wrote a 4,000-word essay on her experiment and findings. It’s packed with physics calculations and technical explanations of her findings, but also describes the results in layman’s terms.
“The coefficient of friction on racing speed suits is significantly more than that of regular snow pants that recreational skiers would wear. This was shown in the incline plane and on the ski mountain,” Marolt wrote in her essay.
“This can be concluded from this experiment because the speed suits all had higher coefficients of friction than the Obermeyer ski pants, which are manufactured for warmth and functionality, as Obermeyer said in the interview.”
The one exception she found was the training pant made by Spyder. While they are designed for warmth and function, they also are used by skiers for training at high speeds. They had a high coefficient of friction, despite less of an emphasis on aerodynamic design.
Marolt also found that the age of the speed suits played a role in their coefficient of friction. The newest of the three giant slalom suits had the highest coefficient of friction, so it’s better at slowing a fallen racer.
Marolt said she learned a lot about the safety of skiing through her experiment with friction.
“If ski clothes for recreational skiers could be manufactured with higher coefficients of friction, collision with trees and other skiers could be avoided,” she wrote in her essay. “This would improve the safety of skiing and potentially save lives.”
Her dad, Roger Marolt, also was impressed with her findings, though he noted he is biased.
“As a great number of serious injuries and death for recreational skiers are caused when victims crash and slide into slope-side objects, my daughter is exploring how technology in ski racing suits might be incorporated into recreational skiers’ clothing to prevent tragic events on the slopes,” Roger wrote in an email. “I am wondering if this might be a greater factor in skier safety than helmets.”
Whitley said he was impressed that Jane Marolt was able to overcome the challenges of a lack of snow to craft a viable experiment. He found it interesting that the speed suits were designed to slow skiers down after a fall.
“I had assumed that the sole purpose of the suit was to decrease drag and go faster,” he said.
Whitley also was impressed that Marolt picked a project that has application to a real world issue — in this case, ski-wear safety.
“As a teacher, that’s what we hope for,” he said.
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