Kap 7 balls11/27/2023 In the case of women’s games, the circumference of the ball is 0.65–0.67 m, and the pressure is 48–55 (kilo Pascal’s) (7–8 pounds per square inch atmospheric). The pressure inside the ball-is 90–97 kPa. The ball’s weight must be in the range of 400–450 g, and the ball’s circumference in the range of 0.68–0.71 m. The ball should be waterproof, with no external seams, and not impregnated with grease or other similar substances. The ball must be round, with an inner tube and a self-closing valve. Its physical characteristic specified in the FINA water polo rules. One of the basic sports equipment used is a ball. At any interrupting signal, the clocks must be stopped until the game is restarted, i.e., the moment the ball has left the player’s hand or is touched by the player on a face-off. The game lasts four quarters, and each quarter lasts 8 min. The team consists of seven players (six on the field and a goalkeeper) on the pitch, and there may be five reserve players and one reserve goalkeeper (13 players in total). The water temperature should not be less than 26 ☌. The dimensions of the goals are 3 m wide and 0.9 m high. The matches are played in a swimming pool on a pitch 30 m long, 20 m wide, and more than 2 m deep. It is a goal-scoring team game, the team that scores more goals against the opposing team wins. In Europe, there are also games such as the Champions League or the European League. The top five teams are Greece, Montenegro, Serbia, Hungary, and Croatia. The water polo leaders in the world rankings are mainly teams from Europe. Currently, eight teams play in the Premier League. Water polo was added to the Olympic disciplines in 1900 (Summer Olympics in Paris), and after World War II, the games resumed in 1954. Today, water polo is played in many countries in different age categories by men and women, and it is considered to be one of the most demanding sports regarding the game’s physical and psychological aspects. Games were often nothing more than gang fights in the water as players ignored the ball and usually ended with one man floating to the surface unconscious. If the player came too close to the goal, he was jumped on by the goalie who was allowed to stand on the pool deck. A favorite trick of the players was to place the five-to-nine-inch rubber ball inside their swimming suit and dive under the murky water, then resurface as near to the goal as possible. At first, players scored by planting the ball on the end of the pool with both hands. Scotsman William Wilson developed the first rules of water polo in 1876. The history of water polo dates back to the end of the 19th century. The obtained results from the analysis of the contact angle, as well as the composition and real feedback from the players, indicated the need to standardize the material aspect of the regulations so that the sports results are repeatable every time. In the case of both balls, anisotropies of the structure of the furrows were observed, however, the Mikasa ball is slightly more homogeneous than the Kap 7 ball. The analysis of the surface free energy shows significant differences (Kap 7 32.16 mJ/m 2, Mikasa 36.48 mJ/m 2). To obtain the goal, the measurement of the contact angle, analysis of the material using Fourier-transform infrared spectroscopy, and optical microscopic evaluation were used. This research compared two new balls produced by top companies producing sports accessories (Kap 7 and Mikasa). This paper aims to demonstrate the differences between balls admitted to a league and world championships in composition, surface texture, and the influence of these parameters on the water polo game. The use of modern materials in sports, in terms of chemical composition and surface texture, entails both progress in results and an increasing discrepancy in the technical parameters of the equipment used.
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