AY Honors/Ultimate Disc/Answer Key

A Wham-O Professional Frisbee

Flying discs (commonly called Frisbees) are the general name for any number of discs which are generally plastic, roughly 20 to 25 centimeters (8–10 inches) in diameter, with a lip. The shape of a disc, an airfoil in cross-section, allows it to fly by generating lift as it moves through the air while rotating. The name Frisbee is a registered trademark of the Wham-O toy company, but is often used generically to describe all versions of the flying disc.

Flying discs are thrown and caught for recreation, and as part of many different flying disc games. A wide range of flying disc variants are available commercially. Disc golf discs are usually smaller but denser and are tailored for particular flight profiles to increase/decrease stability and distance. Disc dog sports use relatively slow flying discs made of more pliable material to better resist a dog's bite and prevent injury. Ring shaped discs, known as Aerobies, typically fly significantly farther than any traditional flying disc. There are illuminated discs meant for night time play which use phosphorescent plastic, or battery powered light emitting diodes.

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Games using flying discs

• Ultimate
• Freestyle frisbee
• Disc Golf - the traditional game of Golf played with flying discs (frisbees) instead of clubs and balls.
• Durango Boot
• Double Disc Court
• Guts Frisbee
• Flutterguts
• Friskee
• Disc dog
• Dodge Frisbee
• Goaltimate
• Schtick
• Fricket, (sometimes called Cups, Suzy Sticks, Frisnok or Disc Cricket)
• Hot Box
• Fris-Nok, the traditional Icelandic-Canadian game.
• Flyer Frizbee

Physics

Lift is generated in primarily the same way as a traditional asymmetric airfoil, that is, by accelerating upper airflow such that a pressure difference gives rise to a lifting force. Small ridges near the leading edge act as turbulators, reducing flow separation by forcing the airflow to become turbulent after it passes over the ridges.

The rotating flying disc has a vertical angular momentum vector, stabilizing its attitude gyroscopically. Depending on the cross-sectional shape of the airfoil, the amount of lift generated by the front and back parts of the disc may be unequal. If the disc was not spinning, this would tend to make it pitch. When the disc is spinning, however, such a torque would cause it to precess about the roll axis, causing its trajectory to curve to the left or the right. Most discs are designed to be aerodynamically stable, so that this roll is self-correcting for a fairly broad range of velocities and rates of spin. However, many disc golf discs are intentionally designed to be unstable. Higher rates of spin lead to better stability, and for a given rate of spin, there is generally a range of velocities that are stable.

Even a slight deformation in a disc, called a "Taco," as extreme cases look like a taco shell, can cause adverse affects when throwing long range. It can be observed by holding the disc horizontally at eye level and looking at the rim while slowly rotating the disc.

Trivia

• In the animated motion picture The Secret of NIMH, based on the book Mrs. Frisby and the Rats of NIMH, the main character's name was changed in post-production from "Frisby" to "Brisby" to avoid potential trademark infringements.
• In the film Back to the Future Part III, Marty McFly throws a metal pie dish at a gunman in order to save Doc Brown's life. He notices the dish is stamped "Frisbie Pie Company", giving a fictional origin to the current use of the term.
• Richard Feynman in his book Surely You're Joking, Mr. Feynman! suggests that watching the wobble of a plate tossed in the Cornell University cafeteria stimulated him to develop mathematics that eventually led to his Nobel prize winning work in quantum electrodynamics [1].

See also

• Disc throws
• Frisbeetarianism
• Chakram

Further reading

• Flat Flip Flies Straight! True Origins of the Frisbee® Walter Frederick Morrison and Phil Kennedy, Wormhole Publishers, Wethersfield, CT (June 2006), ISBN 978-0-9774517-4-6
• Frisbee, A Practitioner's Manual and Definitive Treatise Stancil E.D. Johnson, M.D. Workman Publishing Company, New York (July, 1975) ISBN 978-0-911104-53-0
• The Official Frisbee Handbook Goldy Norton, Bantam Books, Toronto/New York/London (July, 1972) no ISBN
• Frisbee Players' Handbook Mark Danna, Dan Poynter, Parachuting Publications, Santa Barbara, California (1978) ISBN 0915516195
• Frisbee Sports & Games Charles Tips, Dan Roddick, Celestial Arts, Millbrae, California (March 1979) ISBN 978-0-89087-233-8
• Frisbee by the Masters Charles Tips, Celestial Arts, Millbrae, California (March 1977) ISBN 978-0-89087-142-3
• Spinning Flight : Dynamics of Frisbees, Boomerangs, Samaras and Skipping Stones, Ralph Lorenz, Copernicus New York, September 2006 ISBN 978-0-387-30779-4

External links

• Ultimate Players Association sports governing body of Ultimate in the USA
• Freestyle Players Association sports governing body of Freestyle Frisbee in the world
• World Flying Disc Federation international sports governing body for all
• Wham-O Frisbee disc website manufacturer of Frisbee brand flying discs
• UK Ultimate Association
• [2]

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