1, the ball
The outside of the ball on the field needs to be uniformly wrapped by textile materials, the color is white or green, and the seams need to be seamless. The size of the ball needs to meet the requirements in Article 4 of Appendix I (the ball is specifically specified in Rule 3) and weighs between 2 ounces (56.7 grams) and 2 1/6 ounces (58.5 grams). . When moving freely from a height of 100 inches (254 cm) to a concrete floor, the height of the bounce should be between 53 inches (134.62 cm) and 58 inches (147.32 cm). When 18 pounds (8.165 kg) of pressure is applied to the ball, the inward elastic deformation should be between 0.22 inches (0.559 cm) and 0.29 inches (0.737 cm), and the rebound deformation after compression should be between 0.315 inches. Between (0.8 cm) and 0.425 inches (1.08 cm). These two deformation data should be the average value obtained after testing the three axes of the ball. In either case the difference between any two data should not be greater than 0.03 inches (0.076 cm).
If you play at an altitude of 4,000 feet (1219 meters), you need to use two other special balls. The first is that the bounce height is between 48 inches (121.92 cm) and 53 inches (134.62 cm), and the internal pressure of the ball is greater than the external pressure. The other aspects are exactly the same as described above. It is called a booster ball; the second ball has a bounce height between 53 inches (134.62 cm) and 58 inches (147.32 cm), so that the internal pressure of the ball is approximately equal to the external air pressure, and can be specified The altitude of the playing field is maintained for more than 60 days, and the other aspects are exactly the same as described above. This ball is usually called zero pressure ball or no pressure ball.
All tests for ball bounce, size and deformation are subject to the requirements of Appendix 1.
The International Tennis Federation will rule on any question as to whether a ball or sample meets the above criteria, or whether it can be approved for use in a competition. Such a ruling may be an act of the International Network itself, or it may be based on the application of all genuine interested persons or any players, equipment manufacturers or national tennis associations, as well as their members. Such applications and awards should be conducted in accordance with the review and hearing procedures of the International Network.
Rackets that do not meet the following requirements are not allowed to be used in competitions conducted in accordance with this rule:
a. The ball striking surface of the racket should be flat. The chords connected to the racket frame should be composed of uniform rules. The chords should be intertwined or combined with each other at the intersection. The samples composed of the strings should be roughly the same. The density of the center must not be less than the density of other areas. The design and stringing of the racket should be such that the front and back sides of the racket are generally consistent in nature when hitting the ball.
b. From January 1, 1997, the total length of the racket frame (including the handle) used in professional competitions shall not exceed 27 inches (73.66 cm). From January 1, 2000, the total length of the racket frame (including the handle) used in non-professional competitions must not exceed 27 inches (73.66 cm). Prior to this, the maximum length of the racket used in non-professional competitions was 32 inches (81.28 cm). The total width of the frame cannot exceed 12 and 1/2 inches (31.75 cm). The total length of the string plane should not exceed 15 and 1/2 inches (39.37 cm), and the total width should not exceed 11 and 1/2 inches (29.21 cm).
c. The frame, including the handle, shall not have attachments or devices unless the attachment is only and very clearly used to limit and prevent the racket from being worn, cracked, vibrated or used to adjust the weight distribution, and its size And the location must also be reasonable.
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