A ball is a round, usually spherical but sometimes ovoid, object with various uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch, marbles and juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black powder weapons use stone and metal balls as projectiles.
Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see bouncing rubber balls (albeit solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials.
Other articles related to "ball, balls":
... paradox, it is possible to obtain k copies of a ball in the Euclidean n-space from one, for any integers n ≥ 3 and k ≥ 1, i.e ... a ball can be cut into k pieces so that each of them is equidecomposable to a ball of the same size as the original ... These results then extend to the unit ball deprived of the origin ...
... S2 then yields a paradoxical decomposition of the solid unit ball minus the point at the ball's centre (this center point needs a bit more care, see below) ... such points, and like the point at the centre of the ball, it is possible to patch the proof to account for them all (see below) ...
... Computed tomography of a football (soccer) (Video) Baoding balls Baseball Basketball Billiard balls Bowling ball (and pin) Lacrosse ball Cricket ball Golf ball next to a hole Rugby ...
... in set-theoretic geometry which states the following Given a solid ball in 3‑dimensional space, there exists a decomposition of the ball into a ... way to yield two identical copies of the original ball ... any two "reasonable" solid objects (such as a small ball and a huge ball), either one can be reassembled into the other ...
... the tiny seam which runs around a cricket ball at 90 degrees to the large, raised seam ... loosening the threads - in order to create conventional swing when the ball is relatively new, more recently, an understanding has evolved that the ... quarter seam, if lifted, can be as easily replaced before the end of the over, when the ball is due to be inspected by the umpires ...
Famous quotes containing the word ball:
“You see much more of your children once they leave home.”
—Lucille Ball (19111989)
“Innings and afternoons. Fly lost in sunset.
Throwing arm gone bad. Theres your old ball game.
Cool reek of the field. Reek of companions.”
—Robert Fitzgerald (19101985)
“Dont tell me what delusion he entertains regarding God, or what mountebank he follows in politics, or what he springs from, or what he submits to from his wife. Simply tell me how he makes his living. It is the safest and surest of all known tests. A man who gets his board and lodging on this ball in an ignominious way is inevitably an ignominious man.”
—H.L. (Henry Lewis)