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Encyclopedia > Soccer ball

A football, when used in the singular, is a ball used to play one of the sports known as football. Three basic shapes are used for balls in the different codes: virtually spherical balls are used in Association football — also known as soccer — as well as in Gaelic football. At the other extreme, a pointed prolate spheroid is used in American football and Canadian football. Rounded spheroid (or "oval") balls are used in rugby football and in Australian Rules football.


American and Canadian football ball

An American football ball

In North America, the term football refers to a prolate spheroid ball which is used to play American football or Canadian football. It is about 11 inches (28 centimeters) long and about 7 inches (18 centimeters) in diameter at the center. Balls are made of four pieces of leather stitched together. A football has a rubber lining, which is inflated to an air pressure of 12 1/2 to 13 1/2 pounds per square inch (86 to 93 kilopascals). The ball weighs 14 to 15 ounces (397 to 425 grams). Leather laces along one seam provide a grip for holding and passing the ball. Footballs used in recreation may be made of rubber or plastic as well.

Association football (soccer) ball

An Association football ball
An Association football ball

The ball used in Association football is a leather ball with which the sport football (soccer) is played. The traditional football's outer covering consists of 12 pentagons and 20 hexagons of leather sewn together. The ball is like the corresponding polyhedron (designated a truncated icosahedron, see picture there), except that it is more spherical, because the faces bulge due to the pressure of the air inside.

It is a model for the buckminsterfullerene (C60) molecule. The diameter of the football and this buckyball are 22 cm and ca. 1 nm, respectively, hence the size ratio is 200,000,000 : 1.

Other designs for footballs exist, mainly being made up of curved strips of leather. There are also indoor footballs, which are made of one or two pieces of plastic. Often these have designs printed on them to resemble a traditional leather ball.

The now familiar black pentagon/white hexagon combination, called the Telstar, became the standard design for most soccer balls since Adidas introduced it to the Mexico World Cup in 1970. However, the new Nike GEO Merlin is currently the official ball of the English Premiership due to its lightweight properties enabling more spin on the ball.

Australian Rules football ball

Gaelic football ball

Rugby football ball

  Results from FactBites:
soccer: Definition and Much More from Answers.com (6543 words)
Soccer is the most popular international team sport, followed by vast, emotional audiences and associated at times with such events as the 1969 “Soccer War” between El Salvador and Honduras and oubreaks of mass hooliganism, notably by British supporters.
In typical game play, players attempt to propel the ball toward their opponents' goal through individual control of the ball, such as by dribbling (running with the ball close to their feet), passing the ball to a team-mate, and by taking shots at the goal, which is guarded by the opposing goalkeeper.
Handling the ball, tripping an opponent, or pushing an opponent, are examples of "penal fouls", punishable by a direct free kick or penalty kick depending on where the offence occurred.
Bending a Soccer Ball -- Mathematically, by Michael Trott (643 words)
The soccer ball tiling is oriented such that one vertex is the north pole, and one vertex of the pentagon that touches the North pole is on the Eastmost meridian.
The morphing is based on a homotopy between a sphere and the stretched projection of the sphere onto a tube along a quarter circle (in toroidal coordinates) connecting the centers of the two slits.
The (final) soccer ball is held fixed in space and the flat net of pentagons and hexagons is wound around it.
  More results at FactBites »



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