Look up in the sky! It's a bird. It's a plane. It's ... a Hawk! With a skateboard under his feet, Tony Hawk practically flies across the skate park. Every twist, turn, and jump looks effortless. "The Birdman," as he is often called, is training for this summer's Boom Boom HuckJam Tour--an extreme sports tour that features skateboarders, motocross riders, and BMX bikers who perform daredevil stunts. And this summer, the stunts promise to be more daring than ever.
As Hawk glides over the smooth, sloping surface of the skate park, he starts to think about his next move. Having invented almost 100 stunts, Hawk knows what makes a good trick--and how to land it safely. To accomplish his amazing feats, Hawk has to practice constantly--and keep some basic science in mind and break Skateboarding Fear
The first ingredient of any skateboarding trick is the ollie, a simple jump off the ground. Getting a skateboard to lift off the ground and stay under your feet is a lot harder than Hawk makes it look.
To start, Hawk bends his knees. By crouching slightly, he lowers his center of mass, or the point of his body where his weight appears to be concentrated. This gives him more control over the board.
Next, Hawk prepares to spring: He raises his arms and straightens his legs while stomping down on the tail end of the skateboard with his back foot. This downward force sends the front of the board into the air and makes the back of the board bounce off the ground. Tony Hawk--and hisskateboard--are airborne!
"To complete the jump, I have to level the board out," says Hawk. To do this, he slides his front foot over the board's rough surface creating friction, or a sticking force. Once the board appears to be stuck to his feet, Hawk lifts his back foot. This allows the board to keep rising.
As the board reaches its peak, gravity kicks in. Hawk must now land: He bends his knees and drops his arms, lowering his center of mass. This gives him better balance to help cushion his landing.
Having completed an ollie, Hawk makes his way to a halfpipe, a U-shaped wooden ramp. Halfpipes can be pretty big, some measuring more than 4.5 meters (15 feet) high. So it's no wonder that riding one of these ramps requires bravery, skill, and lots of energy.
Hawk starts at the top of the U and lets gravity pull him down. This creates kinetic energy (energy of motion). As he glides down the side of the ramp, the kinetic energy builds and helps to propel him up the other side. To reach the top, even more energy is needed. To achieve this, Hawk pulls out a special move.
"When I was young, I was really, really skinny. And because of that, I had a difficult time producing the power I needed," says Hawk. "So I just learned my own techniques." One of these techniques is "pumping."
Tony "pumps" himself by bending his knees at the bottom of the ramp and then standing up straight on the way back up. The motion raises Hawk's center of mass, pushing his weight upward. This gives him enough energy to reach the top of the ramp.
Once at the top, Hawk may grab the wall and fling his feet and board up into the air, or even perform another ollie off the side. It varies a lot. But according to Hawk, one thing is certain: "Science is a crucial part of performing my stunts."
You can watch Tony Hawk and other daredevil athletes perform jaw-dropping stunts at this summer's Boom Boom HuckJam Tour.
Hawk practices hard to safely land each stunt. But he knows that practicing doesn't guarantee safety, so he wears skateboard protective gear: a helmet and elbow pads.
Words to Know
Center of mass--the point on an object where the weight of the object appears to be concentrated
Force--a push or a pull
Friction--a sticking force that slows a moving object
Gravity--the force that pulls all objects towards Earth
Kinetic energy--energy of motion
1. How is Tony Hawk able to skate down a ramp?
() A. His center of mass pulls him down.
() B. Gravity pulls him down.
() C. Friction pulls him down.
() D. Kinetic energy pulls him down.
2. How does Hawk reach the top of a halfpipe?
() A. He pumps his legs.
() B. He builds kinetic energy.
() C. He raises his center of mass.
() D. All of the above.
3. What happens when Hawk raises his center of mass?
() A. He pushes his weight upward.
() B. He pushes his weight downward.
() C. He reduces his weight.
() D. Nothing happens.
THINK ABOUT IT:
How might the forces that help Tony Hawk skate a halfpipe also help you ride your bike down and up a hill?
1. B 2. D 3. A
SCIENCE CONTENT STANDARDS
For Grades K-4
* Position and motion of objects
* Understanding about science
For Grades 5-8
* Motions and forces
* Understanding about science
INTEGRATE YOUR CURRICULUM!
Language Arts--Reading comprehension
Set a Purpose
To learn the science concepts used in skateboarding.
* Tony Hawk got his first skateboard when he was 9 years old. He became a pro when he was 14. At 16, he was considered the best skateboarder in the world!
* The surface of most skate parks is smooth. This reduces the amount of friction that's created when the wheels of a skateboard glide across it.
* Potential energy is stored energy. The higher Hawk is before he starts a trick, the more potential energy he has. Once Hawk starts moving, the potential energy is transferred into kinetic energy.
* What do you know about skateboarding? (Possible answers: it requires a skateboard; most competitions are performed in halfpipes; it involves lots of tricks; Tony Hawk is a popular skateboarder.)
* How might skateboarding be different from driving a car? (Possible answers: Cars rely on motors to work, but skateboards rely on a skateboarder's ability to moue h is body in certain ways; you sit down while driving but stand while skateboarding.)