Cliff Diving:: Water Impact and Video-Analysis

IntroductionIn high diving competitions the platforms are placed at a height that measures from 28 meters: it can imagine the impact with the water at such velocity (24 m/s) that exposes the muscles and the articulations and all the soft parts of the whole organism to abnormal solicitations that must be absorbed in tenths of a second.This pilot work has calculated the influence of the impact with water in high divers and the eventual consequences.High diving, or cliff diving, is a sport that has become very popular in the last fifteen years, and beginning in 2013, in light of the World Swimming Championships, FINA has added it to the official list of swimming disciplines.This highly spectacular discipline complies a series of motor and psychological abilities which imply constant and meticulous preparation on the athlete's part.According to technical trainers and athletes, a growing need to analyze athletic preparation has occurred. If it considers that divers can practice only the day before the competition and not have the possibility to practice on a daily basis, as in other sports. (Poul-Erik Paulev, ed. Al. 2007)Due to this , we've come to need as many elements as possible to support their performance. The aim of the study is to analyze the various segments of technical execution of each single dive executed by the athlete during the competition in order to better prepare and individualize the strengths and weaknesses of the athlete in each single execution. (Yuan Xiong, ed al. 2004)In modern sports the trainer's need to have useful data to analyze the skills of their athletes is growing. When considering high diving, it comes to miss the technical analysis of coded methodological performance for the individualization of errors, which is usually left to the discretion of the singular athletes.The goal of this study is to create a methodological model that will fill, through video analysis, acquiring and elaborating a certain amount of data collected relative to each performance.The impact coefficient was calculated using pre existing data found in literature and a series of parameters that we will see later on. Wanting to evaluate the weight that the diver's body takes on, we've also referred to studies in the aeronautical fields on water impact on objects. (Isard M, ed. Al. 1996)Consider the diver as a cylinder, long and slim (1.71 m in height) and weighing 80 kg and a fall from a height of 28 meters.In the "in air" phase, consider "g" (gravitational acceleration) for which the impact velocity is given by v0=[radical](2*g*h) m/s.In the "water phase" consider the phenomenon of water being put into motion, ignoring any other phenomena that this actions might trigger (friction, etc.). The evaluation of charges is based on the momentum theorem (Von Karman, 1929). From the moment of impact short intervals of time are considered (dt= 0.001 s), for each interval we've considered how far the object penetrated into the water and what water mass was being moved (in the interval "dt", impulse is equal to the quantity of motion) to then calculate force. (Von Karman, T. 1929)Another approximation considered was that the masses of water being put into motion in the following "dt" behaved in the same manner as masses moving at the same speed. The results obtained were compared to those obtained using the formula from Von Karman for the calculation of the pressure of a "Flat Bottomed Float" and with experimental data taken for an impact at a speed of 9. 14 m/s.The results obtained show that based on the surface impact, a body takes the maximum charge when it is partially submerged. This is verified with the following numbers: 12994,525 [N] in a "dt" of 0,001s ( at 9,14 m/s , 4,25 m in height, maximum force 3661,86 [N]). Now we must evaluate G (vs. "dt") that the body takes on and its possible consequences. (Table 1)The graphic (Graph 1 ) shows that a diver of 80 kg with a surface impact equal to 0,000508 m2 (foot in hyperextension) jumping from a height of 28m finds its highest stimuli at 12994,525 N at 1. …