Re: Why are tennis balls fuzzy

I turn to The Physics of Sports, edited by Angelo armenti, Jr. to answer this question. Several articles written by Howard Brody, some reprinted from The Physics Teacher and others from American Journal of Physics, appear in this book. Professor Brody discusses the impact of the tennis ball with the racket and the ground with actual experimental measurements in fine detail. The key point to the ball-ground collision is whether or not the ball skips/slides when it hits the ground or whether it rolls. The Physics of Sports also contains a very interesting article Kinematics of an Ultraelastic Rough Ball by Richard L. Garwin that is reprinted from American Journal of Physics.

I have answered related questions for the MadSci before:

http://www.madsci.org/posts/archives/jun99/928860654.Ph.r.html
http://www.madsci.org/posts/archives/jun99/928261880.Ph.r.html

A fuzzy tennis ball will have more friction with the ground or racket than a smooth tennis ball, so the ball is more likely to roll when striking the ground instead of sliding. And if a fuzzy ball does slide, it will lose more energy than a smooth ball. A fuzzy ball will grab the court more than a smooth ball, so topspin, backspin, and side spin will have more of an effect when bouncing off the ground. Therefore, a fuzzy ball will emphasize the different characteristics of court material. With a smooth, low friction ball, grass, clay, rubberized concrete, or even asphalt will all play very similarly.

Another thing to consider: I believe part of why tennis balls are fuzzy is based in tradition. Tennis has been around in some form since the late 12th century (http://www.eng.auburn.edu/users/owingka/) before rackets were used and the players struck the ball with their hands. The first tennis balls were probably made from cloth or at least the cover was made of cloth so it probably got fuzzy as the game was played.

Sincerely,

Tom "Serve and Stumble" Cull