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.
Available from www.racquettech.com, amazon.com etc (only $11 for priceless information!)
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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 and TENNIS
STATISTICS
This is a pretty picture of a golf
ball and an 8mm thick slice of a large superball sitting on a slab of polished
granite. The ball spins faster when it bounces off the superball slice since the
tangential coefficient of restitution is much larger. A golf ball that spins
faster will travel further.
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FORENSIC
PHYSICS
Some cases I have worked on with NSW Police and Coroner ______________________________________________________________
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.
PUBLICATIONS
(and TENNIS MAGAZINE
ARTICLES)