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":
... decomposition of the solid unit ball minus the point at the ball's centre (this center point needs a bit more care, see below) ... However, there are only countably many such points, and like the point at the centre of the ball, it is possible to patch the proof to account for them all ...
... picked at' - 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 can be lifted on one side, presumably with ... over alters the balance of air pressure surrounding the ball as it travels through the air and help it reverse ... can be as easily replaced before the end of the over, when the ball is due to be inspected by the umpires ...
... Using the Banach–Tarski 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 ...
... Computed tomography of a football (soccer) (Video) Baoding balls Baseball Basketball Billiard balls Bowling ball (and pin) Lacrosse ball Cricket ball Golf ball ...
... which states the following Given a solid ball in 3‑dimensional space, there exists a decomposition of the ball into a finite number of non-overlapping ... together in a different way to yield two identical copies of the original ball ... implies that given any two "reasonable" solid objects (such as a small ball and a huge ball), either one can be reassembled into the other ...
Famous quotes containing the word ball:
“I dont like comparisons with football. Baseball is an entirely different game. You can watch a tight, well-played football game, but it isnt exciting if half the stadium is empty. The violence on the field must bounce off a lot of people. But you can go to a ball park on a quiet Tuesday afternoon with only a few thousand people in the place and thoroughly enjoy a one-sided game. Baseball has an aesthetic, intellectual appeal found in no other team sport.”
—Bowie Kuhn (b. 1926)
“The ball loved Flick.
I saw him rack up thirty-eight or forty
In one home game. His hands were like wild birds.”
—John Updike (b. 1932)
Big as the ball of my thumb, and dumb as eyes
Ebon in the hedges, fat
With blue-red juices. These they squander on my fingers.
I had not asked for such a blood sisterhood; they must love me.”
—Sylvia Plath (19321963)