Weird science: Skiing faster than terminal velocity
Image from www.lesarcsnet.com
Today the Washington Post tackled the question how skiers can hit higher speeds than a skydiver without a parachute.
Depending on which sources you trust, the record is somewhere between 145 and 156 mph. That's sort of amazing, because it's faster than the terminal velocity of a human body free-falling through the air in the classic belly-down arms-out position -- about 125 mph. (Your mileage may vary.) How is that possible?
Basically, it comes down to two factors: heat and form.
Form is important because the parachute-free skydiver is likely flailing in a not altogether aerodynamic fashion. A local scientist's research illuminates the heat side of the equation:
University of Colorado physicist David Lind once calculated that the total heat generated under a ski could reach 360 watts, the equivalent of six 60-watt bulbs. By contrast, when it's too cold for this "meltwater lubrication" to form, say at around 15 below zero, even the best ski bottoms (typically made of high-density polyethylene, as are grocery-store milk jugs) can start to grate on you, acting like sandpaper and raising the probability of a Full Face Plant, a high-impact version of extreme cosmetic makeover.
Keep that in mind the next time you're out carving in near-Absolute Zero temperatures at Loveland.
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