# Science of Skateboarding

## PHYSICISTS EXPLAIN TRICKY SKATEBOARD PHYSICS

July 1, 2007

Basic physics can explain how skateboarders are able to do those amazing tricks and why some are impossible. Newtonıs Laws of Motion explain everything from transferring energy through your body to build speed to manipulating the board's center of gravity to keep it attached to your feet in the air.

## Science Insider

BACKGROUND: When it comes to skateboarding, thereıs a lot of physics involved. Having a basic understanding of physics can help you learn skateboarding tricks a bit faster. You can calculate whatıs possible if you practice enough, and what kinds of moves are impossible because of the laws of physics.

FORCE OF GRAVITY: Skateboarders rely on gravity to supply the force needed to get them moving. They push off the ramp's ledge. Gravity pulls on the board and they accelerate down the ramp. The faster a skateboarder goes, the higher he can fly when he launches off the ramp's opposite side. More height means more time to execute tricks, resulting in more points from the judges. The taller the ramp, the more gravitational potential energy will be stored when the skateboarder is at the top. Skateboarding half-pipe ramps are typically 15 feet high. All that potential energy converts into kinetic energy on the way down. The kinetic energy gained is converted back into potential energy as the skateboarder shoots up the opposite side of the ramp.

TURN, TURN, TURN: Skateboarders make turns by 'carving': leaning their weight on their toes to push that side of the board into the ground, causing the edge of the board beneath their heels to pop off the ground. Pushing against the ground on the left will produce an equal and opposite reaction to the right, just like Newton's third law of motion says. The more force you exert on one side of the board, the greater your acceleration will be in the direction of that force. So the more a skateboarder leans to one side, the quicker he (or she) will turn in that direction.

STICKING IT: The biggest challenge is to keep the skateboard near your feet at all times, even though youıre not strapped in, as you would be in snowboarding. The secret, once again, is Newton's third law of equal and opposite reactions. When a skateboarder reaches the far side of a ramp, he stomps down on the tail end of the board. The ramp will respond with an equal and opposite force, pushing the board off the ramp and into the air. Even in midair, the friction from the shoe soles and the upward push of the skateboard will keep the board close to his feet.

The American Association of Physics Teachers and the American Physical Society contributed to the information contained in the TV portion of this report.

## Did you know?...

Each year, skateboarding is responsible for about 50,000 visits to the emergency room in the US. More than 1500 are children and adolescents. Most cases are injuries from not wearing a safety helmet.

TO GO INSIDE THIS SCIENCE:
James Riordon
American Physical Society
301-209-3238
riordon@aps.org