Tennis ball

Tennis balls at the 2012 French Open

A tennis ball is a ball designed for the sport of tennis. Tennis balls are fluorescent yellow at major sporting events,[1][2] but in recreational play can be virtually any color. Tennis balls are covered in a fibrous felt which modifies their aerodynamic properties, and each has a white curvilinear oval covering it.

Specifications

Modern tennis balls must conform to certain criteria for size, weight, deformation, and bounce criteria to be approved for regulation play. The International Tennis Federation (ITF) defines the official diameter as 6.54–6.86 cm (2.57–2.70 inches). Balls must have masses in the range 56.0–59.4 g (1.98–2.10 ounces). Yellow and white are the only colors approved by the ITF, and most balls produced are a fluorescent yellow known as "optic yellow", first introduced in 1972 following research demonstrating they were more visible on television.

Tennis balls are filled with air and are surfaced by a uniform felt-covered rubber compound. The felt delays flow separation in the boundary layer which reduces aerodynamic drag and gives the ball better flight properties.[3][4] Often the balls will have a number on them in addition to the brand name. This helps distinguish one set of balls from another of the same brand on an adjacent court.[5]

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 254 cm (100 inches) onto concrete; a bounce between 135 and 147 cm (53 and 58 inches) is acceptable—if taking place at sea-level and 20 °C (68 °F) with relative humidity of 60%; high-altitude balls have different characteristics when tested at sea-level.[6]

Other Languages
čeština: Tenisový míč
dansk: Tennisbold
Deutsch: Tennisball
español: Pelota de tenis
فارسی: توپ تنیس
한국어: 테니스공
עברית: כדור טניס
magyar: Teniszlabda
македонски: Тениско топче
Nederlands: Tennisbal
Plattdüütsch: Tennisball
português: Bola de tênis
slovenčina: Tenisová loptička
svenska: Tennisboll
Türkçe: Tenis topu
Tiếng Việt: Quả bóng quần vợt
粵語: 網球 (波)
中文: 網球 (球)