The rugby ball, why is it so?

The rugby, just like other sports born in England, even if it seems, played among gentlemen. The University of Oxford played an important role in the early years. The book ‘Football Records of Rugby School, 1823-1929’ indicates that the ball, which was never finished, changes over time. It is unknown whether this ellipseoid ball was designed based on the special characteristics of this sport or the opposite. A player of a nineteenth century says: «My last game was in 1864 and the shape of our ball was that of the natural bladder of pork. It was a perfect ball for long stairs or for placing, and also to negotiate. Modern plum is not that good, but it seems to be designed to wear, launch or pass players ».

The shape of the rugby ball may seem strange. It is not. It is closely related to one of the important curves of physics and geometry: ellipse. However, there is no way that the simple physics laws can deal with the movement of a rugby ball after touching the ground. A slight change of each parameter -related parameter of the ball (the speed, the size of the grass, the rotation speed or the leather patch) changes the behavior considerably. It is enough to say that the movement is chaotic. Yet many scientists like to enjoy these problems for the intellectual challenges they offer. The international rugby board indicates that the long axis of the ball must measure between 280 and 300 mm and the length of the central circumference must be between 580 and 620 mm. This means that the inner volume is approximately 6,000 cubic centimeters. Moreover, it plays a fundamental role in entered air.

Standing ball shot (kicking) is a real ceremony. The ball is placed and helps a piece of plastic or mud, with a slope that depends on the distance you want to reach. Then the celebrities come back three steps and two on the sides and the launch of a few briss of grass in the air to assess the wind speed. The kicking race begins that, when kicking, a firm -planted foot must have on the floor, while the other waves at the end of one leg that quickly turns around the hip bone. Two physical concepts are currently applicable: the preservation of the impulse and that of the corner momentum. Moreover, when the kicking touches the ball, only a fraction of energy is intended for its movement. Eventually, while the kicker moves his foot back, he is unbalanced and at that moment the weight of his leg creates a few forces trying to turn his hull. In order to be as balanced as possible when the leg goes back, kicking the opposite arm has to throw forward based on the distance he wants to reach. Moreover, there is the complex movement of the ball, which stays again.