Physics and Acoustics of Baseball and Softball Bats

Dr. Daniel A. Russell
Graduate Program in Acoustics, The Pennsylvania State University

Contents of this website are ©2001-2012 Daniel A. Russell


There is a tremendous amount of physics and engineering that goes into the design of a baseball or softball bat, especially the new high-tech aluminum and composite bats which are currently dominating the market. There is also an amazing amount of physics involved in the bat-ball collision, and in the performance and behavior of the bat itself. My interest in the physics of baseball bats began in 1998 when I was setting up a laboratory experiment for my students and decided to have them look at the vibrational behavior of a youth baseball bat. Now, several years later, vibrational and acoustic analysis of softball and baseball bats has become my primary area of research. I have been able to correlate the vibrational frequencies of bat barrels to measured performance, and have signicantly contributed to an understanding of the trampoline effect in a hollow bat. In addition, my vibrational analysis of the bending modes of a bat has added to the understanding of perception and feel, including why some bats sting more or less than others. My research has been presented before international meetings of the Acoustical Society of America, the International Sports Engineering Association, the Sporting Goods and Manufacturers Association, and the Baseball and Softball Equipment Subcommittee of the American Society for Testing and Materials, and several publications are forthcoming. Included on these webpages are answers to often asked questions concerning the physics of baseball bats. An important distinction for my webpages is that the articles provided below are not opinions, but are based on a thorough reading of the available published research literature as well as results from my own experimental research. A full listing of references is attached to each article so interested readers can look up the facts for themselves. Also included on this site are summaries of my research into the vibrational behavior of bats. I wanted to share with the general public some of the fascinating things my students and I have found.

So, enjoy! And if you find the contents of this page useful or interesting, let me know . If you ask a question, please don't be offended it I don't reply quickly -- between teaching and research I am very busy, and often have trouble keeping up with email questions. And, please don't ask me to do your school science project for you! Doing your own research and reading is much more rewarding than getting all the answers from someone else!


Screenshot from a TV interview which aired on 9/22/05 on the Daily Planet, a daily science/technology show on the Canadian Discovery Channel. This special discussed how some of my research has been used by CE-Composites, a Canadian manufacturer of composite baseball and softball bats. In the screen shot I'm describing how the balance point of the bat affects the swing weight. You can watch the 10-minute interview (follow the Bat Testing 101 link).


Today is The contents (and links) on this page were last updated on May 28, 2012

Disclosure concerning a potential conflict of interest (added 8/2/10)

Scientific answers to frequently asked questions about bats.


I can't remember where I obtained this picture, but I thought a photo of President Bush holding the "Mother of All Bats" was too funny not to share.

My Experimental Research on Bat Vibrations

My Theoretical Models of the Bat-Ball Collision


MLB player Alfonso Soriano making contact on the sweet spot. This photo appeared on the cover of the September 2004 issue of The Physics Teacher to accompany an article about how the cofficient-of-restitution for baseballs depends on humidity.

My Publications and Presentations about Baseball/Softball Bats

Published Articles or Interviews about my Research on Baseball & Softball Bats
I was interviewed for an episode of the Discovery Science program How Do They Do It? which aired starting in February 2007 in the U.S. (Season 3, Episode 4: Fighter Jet, Baseball, Sports Car) Tech in Sports Spells Careers for Engineers My research was described in the Fall 2005 issue of Graduating Engineer Magazine. I was interviewed for a segment of the TV show Daily Planet which aired on the Discovery Channel Canada on September 22, 2005.
The Science of Softball (April 20, 2005) Article posted on the Kettering University News Website and also published in the Summer 2005 issue of the Kettering Perspective. "Playing the Right 'Tune'" - Brief story about my research appeared in the July 2003 issue of Sports Edge Magazine, the official publication of SGMA International (Sporting Goods Manufacturer's Association).

Play Ball! Physics prof helps teach manufacturers how to make a better baseball bat (October 21, 2004). Article posted on KU News website.

Unravelling the physics of the "sweet spot" (April 23, 2003). Article posted on Kettering University News website and also published in the Kettering Perspective

A short blurb about my research on composite baseball and softball bats appeared in the June 2003 issue (Vol. 47, No. 6) of Reinforced Plastics. A photo of me in front of the wall of bats in the acoustics lab was used as a full-page advertisement for Kettering University that appeared in the 2008 Detroit Tigers Yearbook A photo from the same photoshoot was used as marketing material for Kettering University in 2009.

Science Projects Inspired by My Webpages


Bat Manufacturers who have donated bats for use in my research
The manufacturers listed below have graciously sent me bats I requested from them for use in my research studies. However, the research I conduct is entirely my own and while I have shared with them some of the results from my experiments I do not have any official or unofficial affiliation with any of these bat manufacturers.





Other Physics of Baseball & Softball Sites to visit:

Physics of Baseball - an excellent site with tons of information covering the whole spectrum of science and baseball compiled by Dr. Alan Nathan (University of Illinois). Dr. Nathan has contributed significantly to our theoretical understanding behind the bat-ball collision. Sport Science Laboratory - This lab, run by Dr. Lloyd Smith and his graduate students at Washington State University, developed the high-speed cannon test currently used to test and certify all slow-pitch softball bats sanctioned by the Amateur Softball Association. Baseball Research Center - This lab, run by Dr. James Sherwood and his graduate students at the University of Massachusetts at Lowell, tests and certifies every single baseball bat used by NCAA college and Major League Baseball teams. Bomani Sports Research, Inc. - Independent research by a couple of Ph.D. engineers focusing on the issue of safety in softball, specifically the Available Pitcher Reaction Time. Their website includes bat reviews, and research articles, but requires membership to access most information.

Further Reading on the Physics and Technology of Baseball Bats: