when did tennis balls changed from white to yellow
Tennis ball 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.
Table tennis After the 2000 Olympics in Sydney, the ITTF instituted several rule changes that were aimed at making table tennis more viable as a televised spectator sport.[17][18] First, the older 38 mm (1.50 in) balls were officially replaced by 40 mm (1.57 in) balls in October 2000.[7][19] This increased the ball's air resistance and effectively slowed down the game. By that time, players had begun increasing the thickness of the fast sponge layer on their paddles, which made the game excessively fast and difficult to watch on television. A few months later, the ITTF changed from a 21-point to an 11-point scoring system (and the serve rotation was reduced from five points to two), effective in September 2001.[7] This was intended to make games more fast-paced and exciting. The ITTF also changed the rules on service to prevent a player from hiding the ball during service, in order to increase the average length of rallies and to reduce the server's advantage, effective in 2002.[20] For the opponent to have time to realize a serve is taking place, the ball must be tossed a minimum of 16 cm in the air. The ITTF states that all events after July 2014 are played with a new poly material ball.[21] [22]