Presentation on theme: "Tennis and Physics. The and his features Diameter: 6,35 - 6,67cm Wheight: 56,70 - 58,47g Jumphight: 1,346 - 1,473m on hard floor from 2,54m height of."— Presentation transcript:
Tennis and Physics
The and his features Diameter: 6,35 - 6,67cm Wheight: 56, ,47g Jumphight: 1, ,473m on hard floor from 2,54m height of fall (20° C temperature)
Coefficient of impact e The conservation of energy is effective: Definition of the coefficient of impact e: It follows:
Coefficient of impact e It is effective for the :
Different coefficients of impact rubber ball: 0,9 golf ball: 0,84 baseball: 0,5
Experiments of Balldeformity double load = double deformity
Hooke‘s law double force double way of the feather!!!!! Hooke´s law: F = k *x
Period of oscillation and contact time of the Period of oscillation T = ms contact time T/2 = 5 - 6ms
Contact time of the racket The contact time is approximately 15ms! The time is too big to make a contribution for the ball. That means that the racket,,wastes“ energie! The oscillation is available and doesn`t pass over the ball, but loads the wrist and mainly the ellbow. Tennisellbow!
Contact time of the string The contact time is 5 ms and that is the same as that from the ball! Attention: „Vibrastop“ losses the oscillation of the string!
Contact time of the string Different strings are a result of clamping different weights of the strings in the racket. It is effective that there are soft and hard strings. The hard strings are very good for the controlled Top-Spin-Game, but not for very fast and varied game. (Thomas Muster) The soft string is very difficult to play but you can bang very hard and strong balls, because of the elasticity of the soft strings like a trampoline does. (John McÉnroe)
Rotation of the Back-SpinTop-Spin Drive
Magnus effect The Magnus effect has his name of his inventor Gustaf Magnus! No spin of the ball causes that the airstream regularly streams over and under the ball. If you play the spin, the air molecules in the ball‘s felt are carried away.This effectuates that the airstream speads up the ball. Bernoulli-equation Lift or downward pressure!!
The Magnus effect in tennis The Magnus effect is specially set in by playing the back and the topspin. First because the magnus effect changes the trajectory of the ball! To effectuate different effects at the time of the impact of the ball in the field! To change the interplay between the ball and the racket because of the spin!
Reading with the help of the sensors
2 kinds of playing tennis Forehand Serve
What a tennis teacher has to know Principle of independence of the motion! Height of the net: s = 91cm distance of the net-baseline: 12m acceleration of gravity: 10m/s 2
What a tennis teacher has to know s=g/2 * t 2 t 2 = 2s/g t 0,43s v = s/t 28m/s 100km/h
The Speed of the Serve with the Help of the wrist-sensor What you have to know: arm+masse of the racket weigh destine a with the wrist-sensor contact time = 5ms masse of the ball = 0,058kg
The worldrecord of serving: Andy Roddick 150 mph
We hope you have enjoyed our presentation A presentation from: Raphaela Böhm, Petra Fegerl, Evelin Nagelmaier, Verena Weinberger And we are grateful for the help of our teacher MR. BINDER