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Ball
A ball is a round object (usually spherical, but sometimes ovoid) with several 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 or 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 the bouncing rubber balls (although 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. As balls are one of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoamerican Ballgame
The Mesoamerican ballgame (, , ) was a sport with ritual associations played since at least 1650 BC by the pre-Columbian people of Ancient Mesoamerica. The sport had different versions in different places during the millennia, and a modernized version of the game, ''ulama'', is still played by the indigenous populations in some places.Fox, John (2012)''The ball: discovering the object of the game"'' 1st ed., New York: Harper. . Cf. Chapter 4: "Sudden Death in the New World" about the Ulama game. The rules of the Mesoamerican ballgame are not known, but judging from its descendant, ulama, they were probably similar to racquetball, where the aim is to keep the ball in play. The stone ballcourt goals are a late addition to the game. In the most common theory of the game, the players struck the ball with their hips, although some versions allowed the use of forearms, rackets, bats, or handstones. The ball was made of solid rubber and weighed as much as 9 lbs (4 kg), a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball Bearings
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling, they have a much lower coefficient of friction than if two flat surfaces were sliding against each other. Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races. Common ball bearing designs include ''angular contact, axial, deep-groove,'' a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball Game
This is a list of ball games and ball sports that include a ball as a key element in the activity, usually for scoring points. Games that include balls Ball sports fall within many sport categories, some sports within multiple categories, including: *Bat-and-ball games, such as cricket and baseball. * Invasion games, such as football and basketball. * Net and wall games, such as volleyball. *Racket sports, such as tennis, table tennis, squash and badminton. *Throwing sports, such as dodgeball and bocce. *Cue sports, such as pool and snooker. * Target sports, such as golf and bowling. * Hand and ball-striking games, such as various handball codes, rebound handball, and four square. Popular ball games Games that are similar and have a common reference are grouped under the primary name such as bowling, football and hockey. A–E * Angleball * Apalachee ball game ** Crossminton * Bandy ** Rink bandy *** Rinkball * Baseball **Baseball5 * Basketball ** 3x3 (basketball) ** Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sphere
A sphere (from Ancient Greek, Greek , ) is a surface (mathematics), surface analogous to the circle, a curve. In solid geometry, a sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the center (geometry), ''center'' of the sphere, and the distance is the sphere's ''radius''. The earliest known mentions of spheres appear in the work of the Greek mathematics, ancient Greek mathematicians. The sphere is a fundamental surface in many fields of mathematics. Spheres and nearly-spherical shapes also appear in nature and industry. Bubble (physics), Bubbles such as soap bubbles take a spherical shape in equilibrium. The Earth is spherical Earth, often approximated as a sphere in geography, and the celestial sphere is an important concept in astronomy. Manufactured items including pressure vessels and most curved mirrors and lenses are based on spheres. Spheres rolling, roll smoothly in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Projectile
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. Motive force Blowguns and pneumatic rifles use compressed gases, while most other guns and cannons utilize expanding gases liberated by sudden chemical reactions by propellants like smokeless powder. Light-gas guns use a combination of these mechanisms. Railguns utilize electromagnetic fields to provide acceleration along the entire length of the device, greatly increasing the muzzle velocity. Some projectiles provide propulsion during flight by means of a rocket ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juggling
Juggling is a physical skill, performed by a juggler, involving the manipulation of objects for recreation, entertainment, art or sport. The most recognizable form of juggling is toss juggling. Juggling can be the manipulation of one object or many objects at the same time, most often using one or two hands but other body parts as well, like feet or head. Jugglers often refer to the objects they juggle as ''props''. The most common props are balls, clubs, or rings. Some jugglers use more dramatic objects such as knives, fire torches or chainsaws. The term ''juggling'' can also commonly refer to other prop-based manipulation skills, such as diabolo, plate spinning, devil sticks, poi, cigar boxes, contact juggling, hooping, yo-yo, hat manipulation and kick-ups. Etymology The words ''juggling'' and ''juggler'' derive from the Middle English ''jogelen'' ("to entertain by performing tricks"), which in turn is from the Old French '' jangler''. There is also the wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Powder
Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, charcoal (which is mostly carbon), and potassium nitrate, potassium nitrate (saltpeter). The sulfur and charcoal act as fuels while the saltpeter is an oxidizer. Gunpowder has been widely used as a propellant in firearms, artillery, rocketry, and pyrotechnics, including use as a blasting agent for explosives in quarrying, mining, building Pipeline transport, pipelines, tunnels, and road#Construction, roads. Gunpowder is classified as a Explosive#Low, low explosive because of its relatively slow decomposition rate, low ignition temperature and consequently low brisance, brisance (breaking/shattering). Low explosives deflagration, deflagrate (i.e., burn at subsonic speeds), whereas high explosives detonation, detonate, producing a supersonic shockwave. Ignition of gunpowder packed behind a projectile generates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Egypt
Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower Egypt were amalgamated by Menes, who is believed by the majority of List of Egyptologists, Egyptologists to have been the same person as Narmer. The history of ancient Egypt unfolded as a series of stable kingdoms interspersed by the "Periodization of ancient Egypt, Intermediate Periods" of relative instability. These stable kingdoms existed in one of three periods: the Old Kingdom of Egypt, Old Kingdom of the Early Bronze Age; the Middle Kingdom of Egypt, Middle Kingdom of the Middle Bronze Age; or the New Kingdom of Egypt, New Kingdom of the Late Bronze Age. The pinnacle of ancient Egyptian power was achieved during the New Kingdom, which extended its rule to much of Nubia and a considerable portion of the Levant. After this period, Egypt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nausicaa
Nausicaa (; , or , ), also spelled Nausicaä or Nausikaa, is a character in Homer's ''Odyssey''. She is the daughter of King Alcinous and Arete (mythology), Queen Arete of Scheria, Phaeacia. Her name means "burner of ships" ( 'ship'; 'to burn'). Role in the ''Odyssey'' In Book Six of the ''Odyssey'', Odysseus is shipwrecked on the coast of the island of Scheria (Phaeacia in some translations). Nausicaä and her handmaidens go to the seashore to wash clothes. Awakened by their games, Odysseus emerges from the forest completely naked, scaring the servants away, and begs Nausicaä for aid. Affected by the unfortunate hero, she gives Odysseus some clothes and takes him to the edge of the town. Keeping him secret, she goes ahead into town, telling him to go directly to Alcinous's house and make his case to Nausicaä's mother Queen Arete, the family's matriarch. Odysseus approaches Arete and wins her approval, and he is received as a guest by King Alcinous. During his stay, Odysse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Russian Balls 12-13
Russian(s) may refer to: *Russians (), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *A citizen of Russia *Russian language, the most widely spoken of the Slavic languages *''The Russians'', a book by Hedrick Smith *Russian (comics), fictional Marvel Comics supervillain from ''The Punisher'' series *Russian (solitaire), a card game * "Russians" (song), from the album ''The Dream of the Blue Turtles'' by Sting *"Russian", from the album ''Tubular Bells 2003'' by Mike Oldfield *"Russian", from the album '' '' by Caravan Palace *Nik Russian, the perpetrator of a con committed in 2002 See also * *Russia (other) *Rus (other) Rus or RUS may refer to: People * East Slavic historical peoples (). See Names of Rus', Russia and Ruthenia ** Rus' people, the people of Rus' ** Rus, a legendary eponymous ancestor, see Lech, Czech and Rus * Rus (surname), a surname found in ... * Rossiysky (other) * Russian Rive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homer
Homer (; , ; possibly born ) was an Ancient Greece, Ancient Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Despite doubts about his authorship, Homer is considered one of the most revered and influential authors in history. The ''Iliad'' centers on a quarrel between King Agamemnon and the warrior Achilles during the last year of the Trojan War. The ''Odyssey'' chronicles the ten-year journey of Odysseus, king of Homer's Ithaca, Ithaca, back to his home after the fall of Troy. The epics depict man's struggle, the ''Odyssey'' especially so, as Odysseus perseveres through the punishment of the gods. The poems are in Homeric Greek, also known as Epic Greek, a literary language that shows a mixture of features of the Ionic Greek, Ionic and Aeolic Greek, Aeolic dialects from different centuries; the predominant influence is Eastern Ionic. Most researchers believe that the poems w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
