The Physics of Frisbee

FRISBEE PHYSICS How does physics play a role in Frisbee flying?

------------------------------------------------------------------------* How does a Frisbee fly?
* Why is a Frisbee shaped the way it is?
* What would it be like to compete in a world championship Frisbee competition?
* How fast and how far can a Frisbee go?
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Discussion


In the late 1940s Fred Morrison performed some experiments with flying discs. Some of the discs he experimented with were made out of metal while others were formed out of a new material called plastic. In 1955 the Wham-O Company purchased the rights and molds from Morrison. It wasn't until the early 1960s when Frisbees became the rage. Whamo-O's former General Manager Ed Headrick provided the organization and groundwork for the growth of the Frisbee craze. Today organized competitions take place each year around the world culminating in the World Frisbee Competition in California.
Two factors influence the flight of a Frisbee, gravity and air. Gravity acts on all objects the same way, accelerating their mass towards the center of the Earth at 10 meters/second. Once in the air, lift and angular momentum act on the Frisbee giving it a ballet-type performance. Lift is generated by the Frisbee's shaped surfaces as it passes through the air. Maintaining a positive angle of attack, the air moving over the top of the Frisbee flows faster than the air moving underneath it.



Under the Bernoulli Principle, there is then a lower air pressure on top of the Frisbee than beneath it. The difference in pressure causes the Frisbee to rise or lift. This is the same principle that allows planes to take off, fly and land. Another significant factor in the Frisbee's lift is Newton's Third Law which states that for every action there is an equal and opposite reaction. The Frisbee forces air down (action) and the air forces the Frisbee upward (reaction). The air is deflected downward by the Frisbee's tilt, or angle of attack.



Spinning the Frisbee when it is thrown, or giving it angular momentum (gyroscopic inertia), provides it with stability. Angular momentum is a property of any spinning mass. Throwing a Frisbee without any spin allows it to tumble to the ground. The momentum of the spin also gives it orientational stability, allowing the Frisbee to receive a steady lift from the air as it passes through it. The faster the Frisbee spins, the greater its stability.










Angular Momentum--A rotating body's resistance to change in its orientation and rate of rotation. This is similar to gyroscopic inertia.
Angle of Attack--The angle formed by the tilt of the flying disk and the line parallel to the ground.
Bernoulli's principle The pressure in a fluid decreases as the speed of the fluid increases.

Gravity--The force that makes objects move or tend to move toward each other.

Lift--An upward force resulting from decreasing the pressure on the top of an object by increasing the velocity of the air flowing over the top of it.
Newton's Third Law = for every action there is an equal and opposite reaction.