View Full Version : Soccer ball pressure and mass

Bing Yu
11-15-2001, 04:55 AM
Dear colleagues,

I need some help to explain some data we obtained in one of our research
project. One of my students did a study on the impact between soccer
ball and head. She used soccer balls in 3 sizes: size 3, size 4, and
size 5. She inflated each ball to 10 PSI, 12 PSI, and 14 PSI, and
measured ball masses. Here are the results:

Size 3 ball: 10 PSI: mass = 0.19947 kg, 12 PSI: mass = 0.20339 kg, 14
PSI: mass = 0.32404 kg

Size 4 ball: 10 PSI: mass = 0.22305 kg, 12 PSI: mass = 0.22309 kg, 14
PSI: mass = 0.36728 kg

Size 5 ball: 10 PSI: mass = 0.25701 kg, 12 PSI: mass = 0.25981 kg, 14
PSI: mass = 0.42660 kg

The student and a biomedical engineering faculty repeatedly measured the
pressures and masses and confirmed these results are correct. Our
questions is: why did ball masses had significant increases when ball
presure increased from 12 PSI to 14 PSI? Thank you very much for your


Bing Yu, Ph.D.
Assistant Professor
Center for Human Movement Science
Division of Physical Therapy
The University of North Carolina at Chapel Hill
Chapel Hill, NC 27599-7135

Tel: 919-843-8643
Fax: 919-966-3678
E-mail: byu@med.unc.edu

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