Thrills, chills and spills: what keeps two daredevils safe on the slopes? World-class skills and an expert grasp of Physics. (Physical science: Newton's laws of motion).Picabo Street Picabo Street (born April 3, 1971, in Triumph, Idaho) is an American skier, now retired and living in Park City, Utah. She was raised on a small farm in Triumph, several miles southeast of Sun Valley, Idaho, where she learned to ski and race. is one of America's greatest downhill ski racers. She barrels down snowy slopes at speeds up to 80 miles per hour clad in little more than spandex and a helmet. "Speed is in my system," says Picabo (pronounced Peek-a-boo). "I drive fast, talk fast, ski fast." Her mastery of the sport has earned her an Olympic gold Olympic Gold is the official video game of the XXV Olympic Summer Games, hosted by Barcelona, Spain in 1992. It was released for the Sega consoles, Mega Drive/Genesis and Master System, and Sega's handheld, Game Gear. medal and 11 World Cup championship titles. Rebel extreme skier Glen Plake doesn't compete for prizes or titles, but he may be the world's most recognized freestyle skier, thanks to gravity-defying stunts and a trademark 17-inch bleachblond Mohawk. And at age 38 his skills have never been sharper. "I'm in incredible shape," he says. "It's my new calling to let the world know you can hammer for a very long time." Read on to learn how these two thrill seekers use physics to dominate the slopes. IT'S ALL DOWNHILL Any skier can race down a mountain and pick up hair-raising speed thanks to gravity, a downward force that acts on all objects. "Gravity is the hook," says physicist David Lind, author of The Physics of Skiing The Physics of skiing refers to the analysis of forces applied on a skier using the discipline of physics. A common question any analytical thinker might ask is: "Do big people go faster?". The answer is yes, to an extent. . "It's the main force acting on a skier." But let gravity alone do all the legwork leg·work n. Informal Work, such as collecting information or doing research in preparation for a project, that involves much walking or traveling about. and you may find yourself careening The careening of a sailing vessel is laying her up on a calm beach at high tide in order to expose one side or another of the ship's hull for maintenance below the water line when the tide goes out. down a slope like a runaway train. To tame the speed of your descent--and make it to the bottom in one piece--you need to turn, or zigzag, down the slope. A quick clean turn not only keeps you in control, it's the secret to faster race times, explains Lind. Picabo Street knows a thing or two about speedy turns. She's worked on perfecting them since age 9, when she first determined she would one day nab Olympic gold. At 17 she'd conquered nearly every North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. junior ski race. And at the 1998 Winter Olympics in Nagano, Japan, Picabo's Olympic dream came to life. She rocketed her way to a gold medal in the women's Super G event, a daunting daunt tr.v. daunt·ed, daunt·ing, daunts To abate the courage of; discourage. See Synonyms at dismay. [Middle English daunten, from Old French danter, from Latin 600-meter vertical course in Which racers weave around 30 plastic gates rooted in the snow. Whoever completes the turns fastest wins the race. Picabo outperformed the competition by executing each turn at maximum speed--with zero mistakes. Picabo turns with masterful precision in part because she takes full advantage of Newton's third law of motion Noun 1. Newton's third law of motion - action and reaction are equal and opposite law of action and reaction, Newton's third law, third law of motion law of motion, Newton's law, Newton's law of motion - one of three basic laws of classical mechanics : When two objects act on each other they experience equal and opposite forces. So when gravity presses a skier into the snow, the snow exerts an equal and opposite reaction force on the skier. If done expertly, her technique--called carving--leaves a smooth S-shape track in its wake and sacrifices less energy to skidding and vibration. "True carving without skidding results in the optimal ski run," says Lind. "It's the edge of the ski that's biting into the snow and holding you in place." A FORCE TO RECKON WITH to settle accounts or claims with; - used literally or figuratively. to include as a factor in one's plans or calculations; to anticipate. to deal with; to handle; as, I have to reckon with raising three children as well as doing my job s>. See also: Reckon Reckon Reckon Force, of course, is essential to skiing: Without it a skier would be unable to change the direction of her motion. Newton's first law of motion Noun 1. Newton's first law of motion - a body remains at rest or in motion with a constant velocity unless acted upon by an external force first law of motion, Newton's first law describes it this way: An object moving at a steady velocity (speed and direction) keeps moving at that velocity unless acted on by an outside force. In the skier's case, the outside force comes from kinetic, or moving, energy generated mostly by a skier's own leg muscles. But apply too much force--or too little--and disaster can strike. In March 1998, during a World Cup downhill race in Crans Crans is the name or part of the name of several places:
kinetic energy Form of energy that an object has by reason of its motion. The kind of motion may be translation (motion along a path from one place to another), rotation about an axis, vibration, or any combination of into her skis. With no outside force acting on the skis, Newton's first law of motion turned from friend to foe: Picabo's body continued to fly in the direction of her velocity--straight into a fence. The crash shattered her thighbone thigh·bone n. See femur. , or femur femur (fē`mər): see leg. , into nine pieces. "I went from 60 mph to zero in two feet," says Picabo. "It's that loss of control, that moment when you know you're going down, that's terrifying ter·ri·fy tr.v. ter·ri·fied, ter·ri·fy·ing, ter·ri·fies 1. To fill with terror; make deeply afraid. See Synonyms at frighten. 2. To menace or threaten; intimidate. ." "HAIR" BORNE Like Picabo, Glen Plake started skiing as soon as he could walk. But Plake has never won a World Cup nor competed in the Olympics. Racing against the clock is simply not his thing, he insists. Instead, the Lake Tahoe, Nevada native finds glory in freestyle skiing. "It's the creative side of the sport," Plake explains. "Creative" to Glen Plake means finding adventurous ways to battle mogul fields (steep slopes puckered with endless one-meter bumps), or survive midair maneuvers such as the 720-degree twist known as the Rodeo-7. His death-defying specialty: the cliff jump. Plake routinely launches himself off 12-meter rocks and makes picture-perfect landings on wall-steep slopes. How? Consider The Law of Conservation of Momentum: When two objects collide, momentum--an object's mass multiplied by its velocity--is transferred from one object to another. For example, when Plake soars off a cliff his momentum (165 pounds of body weight x 35 mph) is transferred into his landing. If the slope is steep enough, his momentum transfers speed into his downward descent. If the slope is too fiat, momentum transfers directly into his legs. "You can compare it to a NASCAR NASCAR (National Association for Stock Car Auto Racing), organization that sanctions American stock-car races, est. 1948. It held its first race in Daytona Beach, Fla. crash," Plake says. "If a car hits a wall dead on, the driver gets hurt. But if he keeps going, he usually escapes injury." Now who said physics is painful? Force Field: How four forces act on a skier 1 KINETIC ENERGY (KE) KE, or moving energy, is mostly generated froma skier's leg muscles. 2 REACTION FORCE Forces act in pairs. When a skier pushes into the snow, the snow pushes back with equal and opposite force. 3 FRICTION Skintight skin·tight adj. Fitting closely or clinging to the skin. skintight Adjective (of garments) fitting tightly over the body; clinging Adj. 1. clothes reduce friction, a force that resists motion. 4 GRAVITY This downward force acts on all objects on Earth, and accolerates skiers down the slope. Modern Skis: Short, Fat, and Fast Today's hi-tech "parabolic par·a·bol·ic also par·a·bol·i·cal adj. 1. Of or similar to a parable. 2. Of or having the form of a parabola or paraboloid. " skis turn on a dime, thanks to a revolutionary new design borrowed from the snowboard. Like a snowboard, modern skis sport an hourglass hourglass, glass instrument for measuring time, usually consisting of two bulbs united by a narrow neck. One bulb is filled with fine sand that runs through the neck into the other bulb in an hour's time. shape: fat broad tips and tails with a skinny waist. The narrow midsection mid·sec·tion n. A middle section, especially the midriff of the body. helps a skier transfer weight from one edge to another faster and with less power. Says Ken Schielle, mechanical engineer at K2 Inc. "You spend less time on a ski's flat base and more time on its edge." Here's how parabolic skis differ from conventional skis. FAT TIP: Deepens the ski's sidecut The sidecut is a general term for the inner curvature of a ski, snowboard, or skiboard. The sidecut depth is measured as the distance between the waist of the board and an imaginary straight line that strikes both of the contact points at the tip and tail. and makes turning easier; more surface area helps skis "grab" the snow. DEEP SIDECUT: The arc between the ski's tip and tail bands into the snow when pressure is applied to the ski's edge. The bigger the arc, the easier it is to turn. FAT TAIL Deepens the ski's sidecut and makes turning easier; more surface area helps skis "grab" the snow. IT'S YOUR CHOICE CHOOSE THE CORRECT ANSWER TO THESE QUESTIONS: 1 Which statement is FALSE? A A skier uses kinetic energy to change the direction of his/her motion. B Newton's first law of motion relates to an object's speed end direction. C Gravity is e downward force. D Momentum is a force that resists motion. 2 Which force did NOT help Picabo Street win Olympic gold? A gravity B friction C momentum D action/reaction forces 3 Your center of gravity helps maintain A speed. B balance. C momentum. D muscle mass. PICABO STREET Olympic ski racer AGE: 30 BIRTHPALCE: Triumph, Idaho YEARS SKIING: 25 FAVORITE PHYSICS LAW: Acceleration equals force divided by mass (a=F/m) BEST SKI MOMENT: Wining Olympic gold at the 1998 Winter Olympics in Nagano, Japan GLEN PLAKE Extreme freestyle skier AGE: 38 BIRTHPLACE: South Lake Tahoe, Calif. YEARS SKIING: 36 BEST SKI MOMENT: "Anytime I'm skiing for the thrill of speed." SAFETY TIP: "Make sure you stop where someone can see you." Lesson Plans Did You Know? * Why do skis glide on snow? Friction, or rubbing motion, generated when skis press into snow creates a layer of meltwater melt·wa·ter n. Water that comes from melting snow or ice. meltwater Noun melted snow or ice Noun 1. thinner than a light wave. The slick liquid allows skis to glide across the snow's surface. * On an inclined plane, gravity has two components: One component acts parallel to the fall line and accelerates the skier down the slope. The other component acts perpendicular, or normal, to the plane and presses the skier into the snow. * Picabo Street retired from competitive skiing after finishing 16th in the women's, downhill race at the 2002 Winter Olympic Games in Salt Lake City, Utah For ships of the United States Navy of the same name, see . Salt Lake City is the capital and the most populous city of the U.S. state of Utah. The name of the city is often shortened to Salt Lake, or its initials, S.L.C. . Although Picabo is famous for her powerful racing form, the aggressive style clashed with cutting-edge ski technology. "Finding out where and how to put my power into the new parabolic skis is something that I struggled with at the end of my career," says Picabo. "When you apply too much power, the skis respond in a very unnatural way." Cross-Curricular Connection Engineering: The world's leading ski manufacturer has asked you to design a racing ski for the 2006 Winter Olympics. Use pencil and paper pencil and paper - An archaic information storage and transmission device that works by depositing smears of graphite on bleached wood pulp. More recent developments in paper-based technology include improved "write-once" update devices which use tiny rolling heads similar to mouse to sketch three different design concepts. Incorporate at least five new technological innovations that make your skis the world's fastest. Don't forget to name your creations! Critical Thinking: Do you think a national safety-helmet law should be created and enforced for skiing? CHECK FOR UNDERSTANDING Directions: Fill in the blanks to complete the sentences. 1. Skiers can race down a slope with great speed because of this force: --. 2. An object will keep moving at a steady rate unless acted on by a(n) -- force. For skiers, this--or moving, energy is mostly generated by the leg muscles. 3. In the 1988 World Cup races, Picabo Street landed too far back after a jump and threw off her--This caused her to crash into a fence, shattering her --, or thighbone. 4. -- is the force that opposes motion. MATH SKILLS/DEBATE Name:-- Chilling Measurements Scientists--and most of Earth's nations--use the metric system metric system, system of weights and measures planned in France and adopted there in 1799; it has since been adopted by most of the technologically developed countries of the world. as their standard of measurement. But Americans still prefer using the U.S. customary unit. Here are two activities to help you think like the rest of the world. PART 1: COUNT Convert the temperatures on the thermometer diagram (left) from degree Fahrenheit ([degrees]F) to degree Celsius ([degrees]C) by using the following formula: ([degrees]F - 32) + 1.8 = [degrees]C. PART 2: THINK Debate question: Should the U.S. officially adopt the metric system? 1. Divide the class into two teams: for or against the metric system. 2. Research to formulate your argument. Use the points below as a guide. 3. Present your case. You may use graphs and charts as visual aids. For Metrics * The metric system is easier to calculate. All metric measurements are based on units of 10. * Most people on Earth use the metric system. It will ease global communication. * Many everyday products are already measured in metrics. For example: 2-liter soda bottles, 35-millimeter film, and a 200-milligram vitamin pill. Against Metrics * A lot of unnecessary confusion will arise. Why change something that has been working? * Everyday events, from football games to cooking recipes, will have to adopt an entirely new system. * It will cost a lot of money to switch road and other signs to read kilometers instead of miles. Discussion: After the presentation, discuss as a class the pros and cons pros and cons Noun, pl the advantages and disadvantages of a situation [Latin pro for + con(tra) against] of both arguments. Then conduct a class vote to determine if the U.S. should go metric. VOCABULARY BUILDER Name: -- Ski Across the Physics Line Use your knowledge of ski physics to complete the crossword puzzle below. Then unscramble Same as decrypt. See scramble. the words in the parentheses See parenthesis. parentheses - See left parenthesis, right parenthesis. to answer the bonus question. 1. Force divided by mass: --(-) 2. An object's speed and direction: -- 3. Which Newton's law of motion Noun 1. Newton's law of motion - one of three basic laws of classical mechanics law of motion, Newton's law law of nature, law - a generalization that describes recurring facts or events in nature; "the laws of thermodynamics" states that an object in motion stays in motion and an object at rest stays at rest unless acted upon by an outside force? --(-)-- 4. Skintight ski clothes help reduce this force: --(-)-- 5. Downward force that acts on all objects: --(-)- 6. Which Newton's law of motion states that every action has an equal and opposite reaction? --(-)-- 7. An object's mass multiplied by its velocity: --(-)-- 8. Ski technique that leaves a smooth S-shape track: --(-)-- Bonus: Newton's first law of motion is sometimes referred to as "the law of --." ANSWERS CHILLING MEASUREMENTS. Normal body temperature: 37[degrees]C Water freezes: 0[degrees]C Mercury freezes: -40[degrees]C Average surface temperature on Mars: -53.3[degrees]C Coldest surface temperature on Earth: -120[degrees]C Air liquefies: -195.6[degrees]C Average temperature in the universe: -270.6[degrees]C IT'S YOUR CHOICE Thrills, Chills and Spills 1. d 2. b 3. b VOCABULARY BUILDER 1. acceleration 2. velocity 3. first 4. friction 5. gravity 6. third 7. momentum 8. carving Bonus: inertia Resources Introduction to Physical Science, by Ezrailson, Hainen, Lille, McCarthy, Zike, and Zorn, Glencoe/McGraw-Hill, 2002 The Physics of Skiing, by David Lind and Scott Sanders, AIP AIP acute intermittent porphyria. AIP Acute intermittent porphyria Press, 1996 "Carving the Perfect Turn" by David Arnold, The Boston Globe, September 24, 2002 |
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