Catching air: pro-boarder Shaun White uses physics to soar to great heights.
Extreme snowboarding tricks like this one helped Shaun win a coveted gold medal in last February's Winter Olympics. But Shaun's expertise goes far beyond snowy slopes. This 20-year-old athlete is the only snowboarder who is also a pro skateboarder. Since 2003, he has competed against skateboarding legends like Tony Hawk in the Summer X-Games, an annual action-sports competition. Excelling in both sports has earned Shaun a spot on the A-list of action-sports athletes.
Science World interviewed Shaun to find out how the laws of physics help him conquer radical stunts in both skateboarding and snowboarding.
READY, SET, GO!
Whether Shaun is doing flips on his snowboard or catching big air on his skateboard, he relies on Newton's first law of motion for every trick. This law states that Shaun will remain at rest unless acted upon by an outside force (see Nuts & Bolts, p. 14).
He will rely on gravity to supply this external force to his skateboard or snowboard. To get started, Shaun pushes off the ramp's ledge. Then, gravity pulls on his board and he starts speeding down the ramp, says Paul Doherty, a physicist at the Exploratorium in California. The speed Shaun gains by cruising down the ramp is critical for winning contests. The faster he goes, the higher he will fly when he launches off the ramp's opposite side--and the more points he will score with the judges.
Another factor that influences how high Shaun soars is the height of the ramp. Half-pipe ramps are nearly 5 meters (15 feet) tall in skateboarding and 12 m (40 ft) tall in snowboarding. The taller the ramp, the more gravitational potential energy Shaun will store at the top of it. When Shaun pushes the nose of his board down the ramp, that stored energy gets converted into kinetic energy, sending him whizzing down the slope.
As Shaun rockets up the ramp's opposite side, that energy of motion sends him soaring into the air--and gets converted back into potential energy. The higher he goes, the more potential energy he'll have. Also, the higher the jump, the more time Shaun has to do spinning tricks, explains Doherty.
"My favorite thing to do is a really big 360--a full-circle spin," Shaun says.
ON THE EDGE
Before Shaun can catch big air, he needs to be able to skillfully maneuver his board down the slope.
With his feet strapped facing sideways on his snowboard, Shaun makes turns by "carving." When he leans his weight on his toes, that side of his board pushes into the snow, while the edge of the board beneath his heels pops off the ground.
According to Newton's second law of motion, the more force Shaun exerts on one side of his board, the greater his acceleration will be in the direction of that force. So the more Shaun leans to one side of his snowboard, the quicker he'll turn in that direction.
Shaun moves his skateboard in a similar way, but he says it's trickier to control than his snowboard.
STICK TO IT
"Skateboarding is a little more technical than snowboarding because you have to keep the board with you and you are not strapped in," says Shaun.
That's especially hard when Shaun soars off tall ramps. To keep his skateboard near his feet, Shaun relies on Newton's third law of motion. This law states that if one object exerts a force on a second object, then the second object exerts a force of equal strength in the opposite direction on the first object.
How does that apply to Shaun? When he reaches the edge of the far side of a ramp on his skateboard, he stomps down on the board's tail end. That causes the ramp to push up on his board with an equal force. This reaction force pushes the board off the ramp and into the air. Once Shaun is in midair, the friction between his shoe soles and the upward-pushing skateboard helps keep the board snug to his feet.
Controlling his skateboard in midair will be critical as Shaun perfects new tricks. This year, Shaun hopes to complete a 1080, or three midair rotations, on a skateboard. No skateboarder has pulled off this spinning stunt yet. "I have been doing [1080s] on the snowboard, and I thought it would be fun to try it on a skateboard," says Shaun.
With just seconds in the air, Shaun needs a quick reaction time to be able to twist around with lightning-fast speed. "It is just a lot of spinning, and when you are not attached to your board it has to be perfect," says Shaun.
Will this pro athlete land the trick? "I came really close [to landing the 1080] last year, but I think this year might be the year for it," he says.
nuts & bolts
Newton's three laws of motion describe the relationship between a force and the motion of an object. Sir Isaac Newton published the laws in 1687, but physicists still use them to predict how objects move. As Shaun White rides down a half-pipe, Newton's first law predicts that he will keep moving unless acted on by an outside force, like friction.
To learn more about the physics of skateboarding, visit:
JUST DEW IT:
Shaun won his first pro-skateboarding title in the 2005 Dew Action Sports Tour.
Shaun wowed judges with aerial tricks in the 2006 Winter Olympics.
Shaun grabs his skateboard while competing in the Dew Action Sports Tour.
Shaun spun around 720 degrees on his snowboard in the 2004 Winter X-Games.
it's your choice
1 The higher Shaun is off the ground, the more -- he stores.
A kinetic energy
C gravitational potential energy
D muscle power
2 A "1080" in snowboarding lingo is
A three full rotations In the air.
B one backflip.
C a slang term for "good luck."
D the angle of the ramp.
3 What pulls Shaun's board down the ramp?
Jumpstart your lesson with these pre-reading questions:
* Shaun White became a professional snowboarder at age 12. In 2003, at the age of 16, he turned pro in skateboarding. In what ways are these two sports similar? How are they different?
* The "MegaRamp" is the world's highest skateboarding halfpipe. In the Summer X Games, competitors can choose to ride from the MegaRamp's two starting points: One is 19 meters (65 feet) off the ground, and the other towers at 24 m (80 ft). If Shaun White wants to ride at maximum speed, which starting point would he choose?
* In snowboarding competitions, a panel of judges score a boarder's ride based on factors including the following: height of the jumps, quality of rotations, the ride's level of difficulty, and how well the boarder performed the standard tricks. The competitors are also scored on overall impression. How might Shaun White maneuver his snowboard to keep winning medals?
* Each year, skateboarding is responsible for about 50,000 emergency-room visits in the United States. Of those injured, more than 1,500 are children and adolescents who need to be hospitalized. Most of these cases are due to head injuries from not wearing a safety helmet. Severe head injuries can result in disabilities including loss of Vision, hearing, and speech. Study the photos in the article. What safety gear does Shaun White wear while skateboarding or snowboarding?
* Have students select a sport besides snowboarding or skateboarding. Then, challenge each student to explain how Newton's laws of motion are involved in his or her selected sport. Make sure that students cover all three laws.
LANGUAGE ARTS: Divide students into groups. Each group will take on the role of an advertising agency hired by a skateboard-manufacturing company. The mission: Each agency must create a magazine advertisement to market the company's skateboards to the scientific community. To attract these potential customers, be sure to include Newton's laws of motion in the advertisement copy.
* This student-friendly Web site explains the physics of skateboarding tricks: www.kidzworld.com/site/p5207.htm
* For more on Newton's laws of motion, go to: www.physicsclassroom.com/Class/newtlaws/newtltoc.html
* In 1965, Sherman Poppen invented the first snowboard. It was called a snuffer. Learn more about the history of snowboarding at: http://expn.go.com/snb/s/snowboard_timeline_60_70.html
CHECK FOR UNDERSTANDING
DIRECTIONS: Circle the letters of the correct answers.
1. If one object exerts a force on another object, then the second object exerts a force of -- in the opposite direction on the first object.
a. greater amplitude
b. equal acceleration
c. equal strength
d. greater strength
2. When a snowboarder pushes off the top of a half-pipe, -- pulls the boarder down the ramp.
c. potential energy
d. kinetic energy
3. The higher a ramp, the more -- a skateboarder will store at the top of it.
a. kinetic energy
b. gravitational potential energy
c. friction d. mass
4. Newton's -- law of motion states: An object at rest will remain at rest and an object in motion will remain in motion unless acted upon by an unbalanced force.
5. The greater the force exerted on an object, the greater the object's -- will be in the direction of the force.
c. potential energy
In "Catching Air" (p. 12), you learned that Shaun White relies on Newton's laws of motion to tackle high-flying stunts on his skateboard or snowboard. Let's review the laws. Use the article to help you complete the following sections.
Newton's First Law of Motion
1. Shaun White is standing on top of his skateboard, which is resting on the ground. According to the first law, he and his skateboard will remain at rest unless they are acted upon by --.
2. Shaun is tired of standing still. He wants to move forward on his skateboard. What does he need to do in order to move forward? Explain the action in terms of Newton's first law of motion.
3. The law also states: An object in motion will continue moving unless it is acted upon by the answer to question 1. Based on this, what might cause Shaun, who is moving slowly on his skateboard, to stop moving?
Newton's Second Law of Motion
1. According to this law: The greater the force Shaun t exerts on his skateboard, --.
This law can be summed up with this formula:
Force (newtons) = Mass (kilograms) x Acceleration (meters/[second.sup.2]), written as N = kgm/[s.sup.2]
That means that the force on an object is equal to its mass times its acceleration.
2. Suppose a force of 210N is exerted on Shaun and his skateboard, causing them to accelerate at a rate of 3 m/[s.sup.2]. Use the formula to calculate the mass of Shaun and his skateboard.
Newton's Third Law of Motion
1. State the law:
2. Shaun decides to practice his jumps. He, with his skateboard, stomps on the ground with a force of 70N. How much force does the ground push back on Shaun and his board in kgm/[s.sup.2]?
Newton's First Law of Motion
1. an outside force
2. Since Shaun and his skateboard are at rest, they will not move forward unless acted on by an external force. To get Shaun and his board to move forward, have him ask a friend to give him a push. Or have Shaun use one foot to push against the ground. Both methods of pushing can supply the needed external force to set Shaun and his board in motion.
3. Here are some possible sources of outside force that could stop Shaun and his skateboard: Friction generated between the skateboard's wheels rubbing against the road will slow--and eventually stop--the board. Shaun could also stop by putting his foot on the ground. Or Shaun's friend could move in front of him and his skateboard and block them from moving.
Newton's Second Law of Motion
1. the greater his acceleration will be in the direction of the force
2. The total mass of Shaun and his skateboard is 70 kilograms.
Newton's Third Law of Motion
1. If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction of the initial force.
2. 70 kgm/[s.sup.2]
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|Date:||Sep 4, 2006|
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