ROD CROSS HOME PAGE
Why won't this metal
tube "sing" when I hit it with a tennis ball? It does when I hit it
with a golf ball.
Listen to a bell
(recorded at the same volume and ball speed) hit with
(a) a golf ball or (b) a
tennis ball
The bell might sound tinny if you
use internal speakers. Try it anyway as a test of the bass response of your
internal speakers. The fundamental frequency is 975 Hz. Internal speakers will
not respond at all to the f < 200Hz racquet sounds included on the tennis
page.
Brief CV
Born 1943. Lived in Berry, NSW until age 14 then moved to Forbes. B.Sc.
Dip. Ed at Sydney University. PhD in plasma physics in 1968. From 1968 to 1996
I worked in the Plasma Physics Department at Sydney University, specialising in
Alfven wave studies in the TORTUS tokamak. I retired in 2003 as an Honorary
member of staff, to continue work on the physics of sport and forensic physics.
SPORTS
PHYSICS
Superball 1000
f/s (note spin reversal)
TENNIS BALL at 3000 f/s incident
at 30 m/s on clay and on grass
(copyright by ITF). Can be viewed with QuickTime or
RealPlayer and is in H.264 compressed format. Note how clay sticks to the ball
and is then spun off. The grass here was longer than normally seen at
Wimbledon. Grass is a faster surface than clay, even when the grass is long.
You can work out the bounce speed, spin and angle yourself from this film.
TENNIS STRINGS at
1000 frames/sec (using a 725 g boule incident at low speed)
MORE TENNIS
and FIVE WAYS TO WIN A POINT
PUBLICATIONS
(and TENNIS MAGAZINE
ARTICLES)