Air force: the new U.S. women's ski jumping team is taking off. Learn how understanding physics helps these young pioneers soar.
As a ski jumper, 15-year-old Avery Ardovino gets to experience something few people ever will-the feeling of flying. In this extreme sport, Avery shoots down a steep snow-covered ramp at speeds up to 97 kilometers (60 miles) per hour. Then, she launches into the air. "Your fly more than the length of a football field," says Avery. "It's unlike anything else."
Avery is the yougest and newest member of the U.S. women's ski jumping team. Even though her sport is one of the most thrilling spectacles at the Winter Olympics, it's the only Olympic sport not open to women competitors.
The six young athletes on the newly formed team are hoping that they will eventually get to compete in the Winter Olympics. For now, the girls continue to work to take women's ski jumping to new heights, winning medals at various other competitions around the world.
TAKING THE STAGE All of the team members have been jumping practically since they were able to stand on skis. Avery started when she was 8. She practiced on larger and larger hills until, at age 12, she was ready to attempt an Olympic-size jump.
Professional ramps like the ones the girls train on in Park City, Utah, can be built directly into hillsides, or they can be freestanding structures towering more than 10 stories tall. To get to the top, jumpers either climb hundreds of steps or ride a lift. There they fit their long skis into two narrow grooves in the snow and wait for a signal indicating it's safe to take off down the monstrous hill.
Unlike downhill skiers, ski jumpers don't need ski poles to propel themselves down the ramp, or inrun (see Nuts & Bolts, p. 9). "The only major force helping them down the hill is gravity," says Peter Vint, senior sports technologist at the Performance Services Division of the U.S. Olympic Committee. This downward force acts on all objects, turning the girls' gravitational potential energy (stored energy due to height) into kinetic energy, or the energy of motion.
WHAT A DRAG!
The goal of a jump is to fly the longest distance once airborne, and to keep good form all the way to the landing. To maximize distance, jumpers try to reach top speeds while racing down the inrun. In the roughly six seconds it takes to whoosh down the incline, "All you can feel is the wind going through your helmet," says team member Abby Hughes, 18.
That rushing air creates air resistance, or drag, a force that slows down Abby and her teammates. To allow the air to flow more easily around their bodies, the girls' crouch down, with their heads lowered and arms held back along their sides. This aerodynamic position leaves a smaller surface area for air to push against.
The girls also have to fight friction. This resistance to movement occurs as their skis rub against the icy surface of the inrun. "Warmer or colder temperatures can cause the snow crystals to change, and that can affect how fast you go," says Dave Jarrett, a coach for the U.S. ski team. So before a run, jumpers apply wax to the bottom of their skis for a smoother slide down the hill.
Going the distance isn't all about speed, though. "Speed helps you go farther, but technique will always give you the best jump," says Avery. One wrong move could lead to an inflight disaster for the ski jumper.
At the end of the ramp the girls have only moments to put their technique to the test by pushing up and out into their fly positions. After liftoff, the jumpers minimize drag by leaning forward so they are flying headlong through the air. They also spread the front tips of their skis out to create a V-shape.
By flattening themselves out and spreading their skis wide, "a jumper's body behaves much more like a wing," says Vint. This shape causes air to flow faster over the jumper's body than under their skis, creating an area of low pressure above and high pressure below. The pressure difference provides a greater upward force, or lift, to help the jumpers stay aloft longer so they can fly farther--hopefully beating competitors.
STICKING THE LANDING
While the prospect of flying off a man-made mountainside may cause your palms to sweat, seasoned ski jumpers, like those on the U.S. women's team, enjoy the rush. "There's all this adrenaline running through your body," says Abby. "And once you land, you're like, 'I want to do that again!'"
But a flight can't last forever. Eventually gravity pulls a jumper back down to Earth. When they land, the jumpers are required to balance with knees bent and one leg extended past the other.
To touch down gracefully, skiers gauge their speed and distance so they land on the sloped portion of the hill just past the K point, or the target distance of a jump. That allows them to safely transfer some of their momentum (an object's mass times its velocity) into their continued descent down the outrun. If the jumper were to fly too far past this point where the ground levels out, the skier's legs would absorb all the force of the impact leading to a rough landing and a deduction of style points.
Understanding the physics of ski jumping helps members on the U.S. women's team train to be the best. They currently rank among the top-three teams in the entire world, winning top spots at Continental
Cups held in the United States, Canada, and Europe.
As their sport continues to grow, the women's team had been hoping they wouldn't be left out in the cold at the next Winter Olympics in Vancouver, Canada But the International Olympic Committee decided last year that there still aren't enough competitors worldwide to include the sport.
But that's not holding women ski jumpers back. With the formation of the U.S. team last year, women's ski jumping is gaining more recognition. For the first time, in 2009, the girls will get to participate in the Nordic World Championships. "It's a good feeling to be believed in, even though we don't have an Olympic sport," says Abby.
With or without the Olympic Games, the girls are determined to keep their sport thriving for future athletes. "I want to pave the way for jumpers even younger than myself, and help them get to the Olympics," says Avery.
nuts & bolts
Ski jumpers are scored on their technical style and distance. Jumpers gain or lose points if they pass or land short of the K point. This spot is considered the ideal jumping distance and is based on the size of the ramp. Women compete on hills with a K point located 90 meters (295 feet) from the foot of the ramp.
THE INRUN: Ski jumpers crouch into a more aerodynamic position to help them gain speed as they ski down the steep ski jump hill. They leave the ramp traveling at speeds up to 97 kilometers (60 miles) per hour.
THE JUMP: Jumpers have less than a second to push up off the ramp and launch into the air. Once airborne, athletes are only about 4.6 m (15 ft) above the landing hill.
THE FLIGHT: To fly as far as they can, jumpers lean forward and position their skis into a V-shape. This helps them catch more air, keeping them aloft longer.
HE OUTRUN: Jumpers are required land with one leg front of the other, and remain balanced s they ski through " the outrun.
Watch an interview with members of the U.S. women's ski-jumping team they discuss their dreams to complete in the Winter Olympics, at: ww.wsjusa,com/abc2.htm
1. The goal of a successful ski jump is to
(A) jump the highest.
(B) perform the most difficult tricks.
(c) jump the farthest with the best style.
(d) make it down the hill the fastest,
2. What is another term for air resistance?
3. Female ski jumpers can compete in which of the following events?
(A) Winter Olympics
(B) Continental Cups
(C) Nordic World Championships
(D) both b and c
4. To be as aerodynamic as possible, ski jumpers
(A) crouch down on the inrun.
(B) place their arms out in front of them at all times.
(C) remain upright after they take off from the ramp.
(D) keep their skis parallel during their flights.
1. c 2. a 3. d 4. a
DID YOU KNOW?
* Norwegian Bjorn Einar Romoren holds the current ski-jumping record. In 2005, he jumped a distance of 239 meters (784 ft) in Planica, Slovenia.
* Should all events at the Olympics be open to both male and female competitors? Explain your reasoning.
HISTORY: Who was Daniel Bernoulli? Do research and write a short summary on his contribution to science. Then create a diagram to show how Bernoulli's Principle could help a ski jumper soar to great heights.
* To learn more about ski jumping, visit: www.skijumpingcentral.com
* Learn more about the science of flight at: http://acam.ednet.ns.ca/curriculum/science.htm
DIRECTIONS: Use complete sentences to explain how the following forces affect ski jumpers.
2. Air resistance:
5. In the space to the right, make a stick-figure drawing showing the "fly position" that ski jumpers adopt to gain lift.
1. Gravity is the major force that propels ski jumpers down the hill The downward force turns the ski jumpers' gravitational potential energy into kinetic energy.
2. Air rushing past ski jumpers creates air resistance. This force will slow ski jumpers down To minimize drag, ski jumpers maintain a more aerodynamic position that leaves a smaller surface area for air to push against.
3. Friction is the resistance to movement that occurs as the skis rub against the icy surface of the inrun, Skiers try to minimize this slowing force by waxing their skis
4. Lift is an upward force that helps ski jumpers fly farther and stay aloft longer. Jumpers lean forward and position their skis in a V shape This position allows a body to behave more like a wing flying against air flow and gain lift.
5. The stick figure's body should resemble the pose on this issue's cover or the pose on p. 8.
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|Title Annotation:||PHYSICAL: AERODYNAMICS|
|Article Type:||Cover story|
|Date:||Jan 14, 2008|
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