engleski

Mechanics model of relation between body mass of ski jumpers and length of the ski jump

The main purpose of this study was to simulate the influence of a ski jumper’s mass on the ski jump length and flying time regardless of whether the values of other parameters used in the computer simulation procedure are constant. The simulation was made for a jumping hill HS 120m with a maximum inclination of 35 degrees. Initial velocities at take off were vx = 27 ms- 1 and the vertical take-off velocity was vy = 2.5 ms-1. The simulated ski jumper’s frontal area was 0.15 m2 and their longitudinal area was 1.2 m2. The air density factor was 1.0 kg/m3 and the inclination of the ski jumper’s upper body in relation to the direction of the in-flight movement was 35 degrees and did not change during the flight. The ski jumper’s mass varied between 60 kg and 70 kg. The simulation started by inputting the minimal initial jumper’s mass value. Apart from the jumper’s body mass, all input parameters were held constant and had the purpose of calculating the position of the ski jumper’s centre of mass every 0.001 second. The results show that for each extra kilogram of a jumper’s total body mass the length of the ski jump is reduced by about 25 cm. The flying time was longer for lighter jumpers. The time difference between a jumper’s body mass of 60 kg and 70 kg was 0.19 sec. The simulation results show significant differences in the criterion variable length of the jump. Increasing the same jumper’s body mass by 2 kg could mean better or worse results in ski jumping. The International Ski Federation must take some steps to better resolve this unfair problem in the future. Two ski jumpers with a different body mass currently differ in their jump length even though they use the same equipment and perform all phases of the ski jump technique identically.

morphology ; Nordic sports ; computer simulation

nije evidentirano