Dusko Bjelica1, Marija Bubanja1, Jovan Gardasevic1, , ,
1University of Montenegro, Faculty for Sport and Physical Education, Niksic, Montenegro
2
The Dependence of Repulsion Tennis Ball from the Air Pressure in it
J. Anthr. Sport Phys. Educ. 2018, 2(4), 77-82 | DOI: 10.26773/jaspe.181014
Abstract
The aim of this study is to determine the elastic (reflective) properties of the tennis ball depending on the air pressure in it. The standard tennis ball was released on a flat, solid surface from a height of nine meters, three times. For a tennis ball pressure was measured based on the time and rebound of the ball after the first, second and third falls. In the first release the air in the ball was under prescribed pressure. After the first release, the pressure in the ball is reduced by the fact that the ball once is stabbed with a hollow medical needle, after the second release, the pressure in the ball is reduced further by the ball being pierced twice with a hollow medical needle. The setting of the experiment was done by filming the free fall of the prescribed tennis balls and a series of rebounds after being rejected from a solid surface. It can be concluded that the distance traveled and the total duration of four successive reflections largely depended on the internal pressure. In this study, the initial tennis ball velocity was unchanged and only internal pressures were changed. It was determined how much the rejection rate was reduced and the duration of the re-acceleration, depending on the reduction of the internal pressure. All in all, it can be concluded that the initial speed of the ball can be increased by increasing the internal pressure in the ball.
Keywords
Tennis, Ball, Repulsion
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