Introduction
The ollie is the foundation for most skateboarding tricks. Mastering it opens the door to more advanced techniques like kickflips and grinds.
Preparing for the Ollie
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Stance: Place your back foot on the tail and your front foot near the middle of the board.
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Balance: Practice standing on the board with bent knees to find your center of gravity.
Steps to Ollie
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Pop the Tail: Press down hard on the tail with your back foot.
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Slide Your Front Foot: Drag your front foot up the board to create lift.
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Jump: As the tail hits the ground (just a hair before), jump to lift the board.
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Level Out: Use your front foot to even out the board mid-air.
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Land: Aim for both feet landing simultaneously over the bolts for stability.
Troubleshooting Tips
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If the board doesn’t lift, focus on pushing the tail down to snap off of the ground and sliding your front foot more aggressively.
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Practice stationary before attempting while rolling.
The Physics of Performing an Ollie on a Skateboard
The ollie is a fundamental skateboarding trick in which the rider and the skateboard leap into the air without the rider using their hands. This seemingly simple maneuver is a masterpiece of physics, combining principles of mechanics, motion, and force. Understanding the ollie requires breaking it into its component movements and analyzing the forces and motions involved in each step.
Step 1: The Setup
The ollie begins with the skateboarder positioning their feet: the back foot rests on the tail of the skateboard, and the front foot is placed near the middle of the deck. This setup is crucial as it determines how force will be applied and distributed. The skateboard itself is a rigid object supported by four wheels, which act as points of contact with the ground. At this stage, the system is in static equilibrium, meaning all forces (gravity, the normal force from the ground, and friction) are balanced.
Step 2: The Pop
To initiate the ollie, the skateboarder rapidly presses down on the tail of the skateboard with their back foot, causing the tail to strike the ground. This action serves multiple purposes:
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Force Application: The downward force on the tail creates a torque around the rear axle of the skateboard. Torque (τ) is calculated as:
where is the force applied by the back foot, is the distance from the rear axle to the tail, and is the angle between the force vector and the lever arm. This torque causes the skateboard to pivot around its rear wheels.
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Reaction Force: As the tail hits the ground, the ground exerts an upward reaction force on the tail. This reaction force propels the rear of the skateboard upward, initiating the lift.
Step 3: The Drag
Simultaneously with the pop, the skateboarder slides the inner side of their front foot up the deck toward the nose of the skateboard. This action is referred to as the "drag" and serves to level the skateboard in mid-air. The physics of this step involve:
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Friction: The dragging foot generates friction between the shoe and the grip tape of the skateboard. This frictional force allows the rider to exert a forward force on the board, helping to pull the board upward.
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Inertia: The skateboard’s upward motion from the pop combines with the forward motion from the drag. The principle of inertia, as defined by Newton’s First Law, ensures that the skateboard maintains its motion in the absence of external forces.
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Rotational Motion: The drag redistributes the board’s rotational inertia. By moving the front foot upward and forward, the rider shifts the board’s center of mass, which helps counteract the initial torque applied during the pop and aligns the board horizontally.
Step 4: The Jump
While popping the tail and dragging the front foot, the skateboarder simultaneously jumps upward. This action combines several physics concepts:
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Newton’s Third Law: When the rider pushes down on the tail, the skateboard pushes back up with an equal and opposite force. This reaction force contributes to the upward motion of both the rider and the board.
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Momentum Transfer: The rider’s jump transfers momentum to the board. Momentum is conserved within the skateboarder-board system, allowing both to rise together.
Step 5: Mid-Air Control
Once airborne, the rider maintains control of the skateboard by keeping their front and back feet in contact with the deck. This control is crucial for stabilizing the skateboard’s orientation and ensuring a smooth landing. In this phase, the principles of projectile motion come into play:
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Center of Mass: The combined system of the rider and skateboard follows a parabolic trajectory determined by their initial velocity and the acceleration due to gravity ().
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Equilibrium: The rider’s body position and subtle movements keep the skateboard balanced, minimizing angular momentum that could cause unwanted rotation.
Step 6: The Landing
The final phase of the ollie is the landing, where the rider and skateboard return to the ground. Proper landing technique is essential to absorb the impact and maintain stability:
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Impulse and Momentum: The skateboarder bends their knees upon landing to increase the time over which the impact force is distributed. This reduces the impulse () felt by the rider.
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Energy Dissipation: Some of the kinetic energy from the fall is dissipated through the flexing of the rider’s legs and the slight deformation of the skateboard and wheels, ensuring a softer landing.
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Friction and Stability: The friction between the wheels and the ground prevents the skateboard from sliding, helping the rider maintain balance.
The Physics in Skateboarding
The ollie is a perfect example of how physics principles manifest in real-world activities. From the application of torque and friction to the concepts of inertia, momentum, and projectile motion, each phase of the ollie demonstrates the intricate interplay of forces and motion. Mastering the ollie requires not only skill and practice but also an intuitive understanding of these physical principles, which allow skateboarders to defy gravity and perform spectacular aerial tricks.