Tennis and Physics

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Tennis and Physics
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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 fall (20 C temperature)

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Coefficient of impact e
The conservation of energy is effective
Definition of the coefficient of impact e
It follows
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Coefficient of impact e
It is effective for the
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Different coefficients of impact
rubber ball 0,9 golf ball 0,84 baseball 0,5
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Experiments of Balldeformity
double load double deformity
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Hookes law
double force ? double way of the
feather!!!!! Hookes law F k x
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Period of oscillation and contact
time of the
Period of oscillation T 10 - 12ms
contact time T/2 5 - 6ms
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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 doesnt pass
  over the ball, but loads the wrist and mainly the
  ellbow.
• Tennisellbow!

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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!
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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)

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Sweet Spot
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Rotation of the
Back-Spin
Top-Spin
Drive
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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 balls felt are carried away.This
effectuates that the airstream speads up the
ball.
Bernoulli-equation
Lift or downward pressure!!
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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!

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Reading with the help of the sensors
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2 kinds of playing tennis

• Forehand
• Serve

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Forehand
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Rotationtable
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Rotationtable
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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/s2
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What a tennis teacher has to know
sg/2 t2 t2 2s/g t ? 0,43s v s/t ? 28m/s
?100km/h
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Serve
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Serve
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The Speed of the Serve with the Help of the
wrist-sensor

• What you have to know
• armmasse of the racket weigh
• destine a with the wrist-sensor
• contact time 5ms
• masse of the ball 0,058kg

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The worldrecord of serving
13.4.2004 Andy Roddick150 mph
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Rotationtable
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Rotationtable
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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