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Frisbee

Frisbee (also known as Frisbee or disc for short) is a sliding toy or sporting goods, usually plastic, about 20 to 25 cm (8 to 10 inches) in diameter, with lips, used for casual and competitive throwing and catching, for example, in Frisbee games. The shape of the disk (the cross-section is the airfoil) causes it to move in the air during rotation, generating lift, which makes it fly.

Throwing and catching frisbee is a kind of free form entertainment, and also a part of many Frisbee games. There are all kinds of Frisbee variants in business. Golf discs are usually small but dense and are suitable for specific flight situations to increase / decrease stability and distance. The longest disc throwing action recorded was Jr. David Wiggins, with a distance of 338.0m. The disk dog sport uses a relatively slow flying disk made of a more flexible material to better resist dog bites and prevent damage to the dog. There are flying rings, too. They usually go further than any traditional Frisbee. There are also discs for playing at night, which are made of phosphorescent plastic, or contain battery powered light-emitting diodes or electroluminescent rods. Others whistle when they reach a certain speed in flight.

The lift is generated in the same way as a conventional wing. The rotating Frisbee has a nearly vertical angular momentum vector, which can stabilize its angle of attack by gyroscopic action. If the disc does not rotate, it will fall to the ground. However, when the disc rotates, the aerodynamic torque causes it to precess around the axis of rotation, bending its trajectory to the left or right. Most disks are designed to be aerodynamically stable, so the roll is accurate for all speeds and rotational speeds. However, many of the discs are deliberately designed to be unstable. A higher spin rate leads to higher stability, and for a given spin rate, there is usually a series of stable speeds. Even a slight deformation of the disc (called "tacos," which in extreme cases look like a taco shell) can have a negative effect on long throws. The disc can be checked for distortion by keeping it level in the line of sight position and looking at the rim while turning it slowly.

The term Frisbee, commonly used to describe all Frisbees in general, is a registered trademark of Wham-O toys. Although companies do not encourage the use of such names, the use of names as a generic term puts trademarks at risk; as a result, many Frisbee games are now known as "plate" games, such as ultimate or disc golf.

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