Ball (association football) in the context of "Eigil Nielsen (footballer, born 1918)"

Association football, more commonly known as football or soccer, is a team sport played between two teams of 11 players who almost exclusively use their feet to propel a ball around a rectangular field called a pitch.

The objective of the game is to score more goals than the opposing team by moving the ball beyond the goal line into a rectangular-framed goal defended by the opponent. Traditionally, the game has been played over two 45-minute halves, for a total match time of 90 minutes. With an estimated 250 million players active in over 200 countries and territories, it is the world's most popular sport.

A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in warfare and sports (for example, a thrown baseball, kicked football, fired bullet, shot arrow, stone released from catapult).

In ballistics, mathematical equations of motion are used to analyze projectile trajectories through launch, flight, and impact.

In games of association football, teams compete to score the most goals. A goal is scored when the ball passes completely over a goal line at either end of the field of play between two centrally positioned upright goal posts 24 feet (7.32 m) apart and underneath a horizontal crossbar at a height of 8 feet (2.44 m) — this frame is itself referred to as a goal. Each team aims to score at one end of the pitch, while preventing their opponents from scoring at the other end. Nets are usually attached to the goal frame to catch goalscoring balls, but the ball is not required to touch the net.

In mathematics, and especially in geometry, an object has icosahedral symmetry if it has the same symmetries as a regular icosahedron. Examples of other polyhedra with icosahedral symmetry include the regular dodecahedron (the dual of the icosahedron) and the rhombic triacontahedron.

Every polyhedron with icosahedral symmetry has 60 rotational (or orientation-preserving) symmetries and 60 orientation-reversing symmetries (that combine a rotation and a reflection), for a total symmetry order of 120. The full symmetry group is the Coxeter group of type H₃. It may be represented by Coxeter notation [5,3] and Coxeter diagram . The set of rotational symmetries forms a subgroup that is isomorphic to the alternating group A₅ on 5 letters.

Spalding is an American sports equipment manufacturing company. It was founded by Albert Spalding in Chicago in 1876 as a baseball manufacturer, and is today headquartered in Bowling Green, Kentucky. It sells softballs through its subsidiary Dudley Sports. In the past, Spalding has manufactured balls for other sports, including American football, soccer, basketball, volleyball, tennis, and golf. The company invented the first basketball in 1894.

For a brief period in the 1980s, Spalding was also a designer of aftermarket automotive wheels.

Telstar is a football made by Adidas. The iconic 32-panel alternating black-and-white design of the ball, based on the work of Eigil Nielsen, has since become a global standard design used to portray a football in different media.

In geometry, the truncated icosahedron is a polyhedron that can be constructed by truncating all of the regular icosahedron's vertices. Intuitively, it may be regarded as footballs (or soccer balls) that are typically patterned with white hexagons and black pentagons. Geodesic dome structures such as those whose architecture Buckminster Fuller pioneered are often based on this structure. It is an example of an Archimedean solid, as well as a Goldberg polyhedron.