Originated in the 1970s by Alan (Ollie) Gelfand, his eponymous maneuver allows skateboarders to leap and arch over obstacles. But, how exactly is this move accomplished with seamless choreography? From the point of view of the uninitiated, the ollie seems almost mystical. However, when we peel back and define the sum of its parts, the ollie is an orchestrated sequence of balance, movement, and forces applied via the skateboarder's body. It’s all reduced to a few principles of physics - force, torque, Newton’s Third Law and friction. To perform the ollie, a skateboarder unintentionally focuses on two factors - the net force and net torque applied to the board. Force, similar to gravity, pushes and pulls objects in a specific direction and torque rotates objects in a specific direction relative to the object’s pivot point.
As the skateboarder approaches the obstacle; he begins to bend his knees; pull in his arms and close his shoulders in preparation of the vertical thrust necessary to clear the obstacle - essentially pushing down on the ground. However, Newton’s third law states “For every force you apply, there will be an equal and opposite force applied back onto you.” Or otherwise said, the ground will push back at the skateboarder with an equal and opposite force thrusting him into the air. This is also known as “pop”.
During the “pop” phase, the skateboarder opens his shoulders and extends his arms and legs. This orchestrated sequence of events affects the torque of the skateboard. The act of pushing down on the tail of the board causes the back wheels to become a pivot point - the tail end of the skateboard rotates down and the nose rotates up leaving the board at an angle. However, an additional step is further required to clear the obstacle.
As the parabola begins, the skateboarder then uses friction to lift the board even higher. Friction is a force that opposes motion between two surfaces. So in this case, the skateboarder glides his front foot up the grip tape. The opposing interaction of these two surfaces causes the board to move further upward.
But in order for the skateboarder to clear the obstacle, he must then push his front foot down. The act of pushing his front foot down changes the pivot point to the center of the skateboard generating torque against the board once again. The back of the skateboard goes up and the front goes down creating the apex of the parabola.
All that’s left is for the skateboarder to let gravity bring him back down to the ground - bending his knees to absorb the impact.
how it works the international space station How The Ollie Works: The Physics Of Skateboarding's Most Common Trick | |
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