Instruct: Given a question, retrieve relevant documents that answer the question.
Query: What is a tennis ball made out of?
Many companies manufacture and distribute tennis rackets. Wilson, Head and Babolat are some of the more commonly used brands; however, many more companies exist. The same companies sponsor players to use these rackets in the hopes that the company name will become more well known by the public.
Tennis balls were originally made of cloth strips stitched together with thread and stuffed with feathers. Modern tennis balls are made of hollow vulcanized rubber with a felt coating. Traditionally white, the predominant colour was gradually changed to optic yellow in the latter part of the 20th century to allow for improved visibility. Tennis balls must conform to certain criteria for size, weight, deformation, and bounce to be approved for regulation play. The International Tennis Federation (ITF) defines the official diameter as . Balls must weigh between . Tennis balls were traditionally manufactured in the United States and Europe. Although the process of producing the balls has remained virtually unchanged for the past 100 years, the majority of manufacturing now takes place in the Far East. The relocation is due to cheaper labour costs and materials in the region.
The first balls were made of natural materials, such as an inflated pig bladder, later put inside a leather cover, which has given rise to the American slang-term "pigskin". Modern balls are designed by teams of engineers to exacting specifications, with rubber or plastic bladders, and often with plastic covers. Various leagues and games use different balls, though they all have one of the following basic shapes:
Animal intestine is the most resilient material used to make tennis strings. It has better tension retention than any other material, and also is softer than any other material used for tennis strings. It provides the most energy return, meaning it is the most efficient string. It remains soft at high tensions while other materials tend to stiffen dramatically. This allows gut string to enable players to string rather tightly to improve ball control without losing much rebound efficiency (power) and without greatly increasing impact shock, which can hurt the elbow and other joints.
The material used in tennis string can significantly affect a player's performance, and even health. Several materials are used to make tennis strings. They vary in terms of elasticity, durability, rebound efficiency, tension holding capability, and manufacturing cost, among other considerations.
A tennis backboard is a simple wall usually made from some kind of fiberboard and located at a tennis court. It should have a tennis net either drawn or painted at the proper height. It is designed to allow a single person to practice by hitting a tennis ball against the wall so the ball is returned, much like a second player would return it.
In the early 1870s lawn tennis arose in Britain through the pioneering efforts of Walter Clopton Wingfield and Harry Gem, often using Victorian lawns laid out for croquet. Wingfield marketed tennis sets, which included rubber balls imported from Germany. After Charles Goodyear invented vulcanised rubber, the Germans had been most successful in developing vulcanised air-filled rubber balls. These were light and coloured grey or red with no covering. John Moyer Heathcote suggested and tried the experiment of covering the rubber ball with flannel, and by 1882 Wingfield was advertising his balls as clad in stout cloth made in Melton Mowbray.
Purcell designed a low, bleached-white canvas-and-rubber badminton sneaker for the B.F. Goodrich Company, known as PF Flyers in 1935. The shoe would provide better support on badminton courts because of a steel shank embedded in its heel. For most of the twentieth century, Jack Purcell's tennis sneaker was required wear on all grass and clay tennis courts in the United States and, at least for a time, on newer, all-weather asphalt courts as well. Unlike basketball sneakers (running shoes hadn't been invented yet), Jack Purcell sneakers had perfectly flat soles, unmarred by grooves that could tear up clay or grass and skew the elasticity of tennis ball bounces. Everyone from the youngest learner to professional and amateur tennis stars on the international tour wore Purcell sneakers; no other company made them. In 1972, Converse purchased PF Flyers (now owned by New Balance), along with the trademark rights of Jack Purcell sneakers. When Nike purchased Converse in 2003, Jack Purcell sneakers were kept in production, and is still manufactured today. Purcell-type basketball sneakers are now no different from Converse Chuck Taylor All-Stars, except they have the trademark blue across their toes. Classic Purcell tennis sneakers are unchanged in appearance from their heyday in the 1950s and 1960s, when they were first nicknamed "Blue Tips" and "Smilies", but they have risen in price from about $20 in 1965 to as much as $150 or more today. Converse "Jack Purcell" basketball sneakers are also popular, but more for their vintage fashion appeal than for athletic use.
The currently available models have ball capacities of 50-60 balls. Both ball speed range and ball frequencies are adjustable and vary from 30 to 150 km/h and 1.5-12 balls per second, respectively, with the .75 second interval suitable for quick volleys and 10 second interval for other strokes. Changing the speed and frequency of the ball coming out of the machine is intended to help the player to visualize real-game situations where the ball does not always come back into play at the same speed. The adjustable speed is also useful for increasing the speed as the player becomes more skillful.
A balloon is an inflatable flexible filled with air and also gas, such as helium, hydrogen, nitrous oxide or oxygen. Modern balloons can be made from materials such as Natural latex rubber, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders . latex rubber balloons are used for children playing amusement it is cheap toys for rural people's children it also use as decorative purposes, while others are used for practical purposes such as meteorology, medical treatment, military defense, or transportation. A balloon's properties, including its low density and low cost, have led to a wide range of applications. The inventor of the natural latex rubber balloon, (the most common balloon) was Michael Faraday in 1824, via experiments with air and various gases.
Polyolefin is one of the softest synthetic string materials, rivaling some Zyex and most nylon multi-filaments. It offers mediocre durability and tension retention, so it is generally used as the cross string in a hybrid string setup. For those who do not break strings very quickly, however, 100% polyolefin stringing may be a good alternative to natural gut and multi-filament strings. This is especially true for those who have had tennis elbow and find natural gut string to be too costly.
Latex rubber toy balloons were introduced by pioneer rubber manufacturer Thomas Hancock the following year in the form of a do-it-yourself kit consisting of a bottle of rubber solution and a condensing syringe. Vulcanized toy balloons, which unlike the earlier kind were unaffected by changes in temperature, were first manufactured by J.G. Ingram of London in 1847 and can be regarded as the prototype of modern toy balloons.
The only essential equipment in a basketball game is the ball and the court: a flat, rectangular surface with baskets at opposite ends. Competitive levels require the use of more equipment such as clocks, score sheets, scoreboard(s), alternating possession arrows, and whistle-operated stop-clock systems.
A regulation basketball court in international games is long and 49.2 feet (15 meters) wide. In the NBA and NCAA the court is . Most courts have wood flooring, usually constructed from maple planks running in the same direction as the longer court dimension. The name and logo of the home team is usually painted on or around the center circle.
Zyex string offers more rebound efficiency, i.e. gut-like dynamic stiffness, than other synthetic strings, particularly when strung at low tensions. This gives it playability that is more similar to natural gut than, arguably, other synthetic materials. It also has low overall stiffness. The ProKennex IQ Element Z string, for instance, has the lowest stiffness of any synthetic string yet tested. The drawback of Zyex is that the outer wrapping materials in Zyex tennis string tend to be much less durable than the Zyex filaments inside the string and do not bond with them. This can lead to the outer wrapping wearing away, leaving the inner Zyex filaments.
Different clubs use slightly different court sizes, with the hosts of any given tournament permitted to choose the court size for that event, but the standard court is 9.45m long by 4.1m wide. It is split in half lengthways by a line and widthways by a net, at a height of 1.75m, with each player (in singles) or team (in doubles) always remaining on their side of the net.
Venus's atmosphere is made mostly out of carbon dioxide, which, after filtering from sulfuric acid, can be used to grow food. Because nitrogen and oxygen are lighter than the carbon-dioxide that makes the atmosphere, breathable-air-filled balloons will float at a height of about . At this height, the temperature is a manageable ; or if we could get higher (see ).
In Europe, early footballs were made out of animal bladders, more specifically pig's bladders, which were inflated. Later leather coverings were introduced to allow the balls to keep their shape. However, in 1851, Richard Lindon and William Gilbert, both shoemakers from the town of Rugby (near the school), exhibited both round and oval-shaped balls at the Great Exhibition in London. Richard Lindon's wife is said to have died of lung disease caused by blowing up pig's bladders. Lindon also won medals for the invention of the "Rubber inflatable Bladder" and the "Brass Hand Pump".
The "blade" of a cricket bat is a wooden block that is generally flat on the striking face and with a ridge on the reverse (back) which concentrates wood in the middle where the ball is generally hit. The bat is traditionally made from willow wood, specifically from a variety of white willow called cricket bat willow ("Salix alba" var. "caerulea"), treated with raw (unboiled) linseed oil, which has a protective function. This variety of willow is used as it is very tough and shock-resistant, not being significantly dented nor splintering on the impact of a cricket ball at high speed, while also being light in weight. The face of the bat is often covered with a protective film by the user.
A pachinko machine resembles a vertical pinball machine, but is different from Western pinball in several ways. First, a pachinko machine uses small (11 mm diameter) steel balls, which are rented to the player by the owner (usually a "pachinko parlor," featuring many individual games in rows), while pinball games use a larger, captive ball. The pachinko balls are not only the active object, but are also the bet and the prize. The player loads one or more balls into the machine, then presses and releases a spring-loaded handle, which is attached to a padded hammer inside the machine, thus launching the ball into a metal track. The track guides the ball around the edge of the playing field, then when the ball loses momentum, it falls into the playing field from near the top. Some pachinko machines have a bumper to bounce the ball as it reaches the top, while other machines allow the ball to travel all the way around the field, to fall on the second time that it reaches the top.
The material of choice for producing these screws is stainless steel typically 18-8 (303). At the tip of the screw most commonly a stainless steel ball is either pressed or glued into place to provide a single point contact for the surface being moved. Common usage has shown the glue method of attaching the ball to be troublesome in many applications as some commonly used glues (Super Glue) tend to outgas and degrade over time in this application.
Two competitors play with a ball, in an arena which is split into two halves with breakable blocks on both sides. The aim is to get a higher score than your opponent by breaking more blocks on your side than your opponent does. Competitors are in the form of humanoids, robots and aliens, all of which have a 'gun' of some sort enabling them to take control of the ball. The range of arenas have several pinball-style flippers which make the ball bounce off at unpredictable angles. The game can be played as one player versus a computer player (controlled with good AI for its time), or as two players competing against one another. Players can suck the ball into their gun then fire it at their blocks for points, or deliberately shoot the ball into their opponent to make them lose points. When hit, players disintegrate but instantly re-spawn with control of the ball going to the opponent.
The first rubber balloons were made by Professor Michael Faraday in 1824 for use in his experiments with hydrogen at the Royal Institution in London. "The caoutchouc is exceedingly elastic", he wrote in the Quarterly Journal of Science the same year. "Bags made of it...have been expanded by having air forced into them, until the caoutchouc was quite transparent, and when expanded by hydrogen they were so light as to form balloons with considerable ascending power..." Faraday made his balloons by cutting round two sheets of rubber laid together and pressing the edges together. The tacky rubber welded automatically, and the inside of the balloon was rubbed with flour to prevent the opposing surfaces joining together.
In tennis, there are a variety of types of shots (ways of hitting the ball) which can be categorized in various ways. The grip you place on will help you have different types of shots, the lower your grip means that the ball is most likely going to be a ground stroke. According to William T. Tilden, "All tennis strokes, should be made with the body' at right angles to the net, with the shoulders lined up parallel to the line of flight of the ball ." The serve is the opening shot of a point. Groundstrokes are hit after the ball has already bounced, and can be either forehands or backhands depending on which direction the racket is swung relative to the body. A lob is a groundstroke hit well over the head of an opponent who is positioned at the net. A passing shot is a groundstroke that is hit out of reach of an opponent at the net far to his left or right. A "cross-court shot" is a shot hit from the left (or right) side of one player's court to the left (or right) side of the other player's court (from each player's own point of view), so that it crosses the lengthwise centerline of the court. A "down-the-line shot" is one that is hit more or less parallel to, and near to, one of the sidelines, so that it never crosses the centerline.
In informal games, either a rubber ball or tennis ball is used as an alternative. The rubber ball is not suitable for the variety of surfaces made use of in informal games; it is too bouncy on cement and concrete and barely bounces at all on grass or soil. An unmodified tennis ball is light, but it is incapable of gaining sufficient speed. By covering a tennis ball with electrical tape, the ball's weight and traction are increased, which in turn leads to greater bounce and speed. A tape ball can also be used to mimic a seaming cricket ball by adding an extra layer of tape around the circumference like a seam, the sides can be roughened to mimic conventional swing of a cricket ball. The tape ball is thus a sound compromise between safety and sincerity to the sport.
Before the development of lawn tennis in the early 1870s, the sport was played as the courtly game of real tennis. England banned the importation of tennis balls, playing cards, dice, and other goods in the Act of Parliament Exportation, Importation, Apparel Act 1463. In 1480, Louis XI of France forbade the filling of tennis balls with chalk, sand, sawdust, or earth, and stated that they were to be made of good leather, well-stuffed with wool. Other early tennis balls were made by Scottish craftsmen from a wool-wrapped stomach of a sheep or goat and tied with rope. Those recovered from the hammer-beam roof of Westminster Hall during a period of restoration in the 1920s were found to have been manufactured from a combination of putty and human hair, and were dated to the reign of Henry VIII. Other versions, using materials such as animal fur, rope made from animal intestines and muscles, and pine wood, were found in Scottish castles dating back to the 16th century. In the 18th century, strips of wool were wound tightly around a nucleus made by rolling a number of strips into a little ball. String was then tied in many directions around the ball and a white cloth covering sewn around the ball.
Tennis balls begin to lose their bounce as soon as the tennis ball can is opened. They can be tested to determine their bounce. Modern regulation tennis balls are kept under pressure (approximately two atmospheres) until initially used; balls intended for use at high altitudes have a lower initial pressure, and inexpensive practice balls are made without internal pressurization. A ball is tested for bounce by dropping it from a height of onto concrete; a bounce between is acceptable—if taking place at sea-level and with relative humidity of 60%; high-altitude balls have different characteristics when tested at sea-level.