June 25, 2011


The Physics of Cheating in Baseball: Corked bats and juiced balls have long plagued baseball, but do they really help a player’s game? Four scientists found surprising answer (Christopher Solomon, June 24, 2011, Smithsonian.com)

In June 2003, Chicago Cubs slugger Sammy Sosa was caught using an illegal corked bat—hardly the first time it’s happened in the Major Leagues. A corked bat is one in which a cavity is drilled out of the barrel and filled with a lightweight material such as cork.

It was scandalous…but does it work? That’s the question that intrigued Alan Nathan, a professor emeritus of physics at the University of Illinois (and a die-hard Red Sox fan). “There was some anecdotal information from players that there’s something like a ‘trampoline effect’ when the ball bounces off a corked bat,” says Nathan, one of the authors of the new study. So the researchers hollowed out a bat, stuffed it with bits of cork and fired a ball at the bat from a cannon. If anything, the ball came off the corked bat with a slower speed than off a normal bat. Less velocity means a shorter hit. Their conclusion: the trampoline effect was bogus.

But there was another way corking might work: a corked bat is a few ounces lighter than an unadulterated one, and a lighter bat means a batter can swing faster, which means he can generate more force and hit the ball farther. Right?

Not quite, as it turns out.

A batter indeed can swing a lighter bat faster, but a lighter bat has less inertia. So there’s a trade-off, says Lloyd Smith, an associate professor of engineering at Washington State University and a co-author on the paper. By once again firing a ball at a bat at WSU’s Sports Science Laboratory, the researchers found that a heavier bat still hit the ball harder (and therefore farther) than a lighter, corked bat. “Corking will not help you hit the ball farther,” says Smith.

Posted by Orrin Judd at June 25, 2011 3:46 PM
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