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The issue of juiced baseballs surfaces every couple years during the month of April due to a high rate of home runs hit. (Ed Wolfstein / Icon SMI 756 / Ed Wolfstein / Icon SMI / Newscom)

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 answers

smithsonian.com

Cheating in sports might be as old as the race between the tortoise and the hare. But not all trickery actually works, especially in baseball.

A corked bat can hit the ball farther, right? That’s a myth, say physicists studying the national pastime. And can making a baseball moister really thwart a slugger from putting one in the bleachers? Well, maybe—depending on how hot it is outside.

To separate fact from fiction, four scientists from three universities spent days firing baseballs at bats. The results are published in “Corked Bats, Juiced Balls, and Humidors: The Physics of Cheating in Baseball” in the June issue of the American Journal of Physics.

To Cork or Not to Cork

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.

“That’s not to say that baseball players are dumb,” Smith is quick to add. Players may have another reason to cork their bats: to make the bats lighter so players can, in baseball argot, “get around on a pitch” quicker, allowing them to wait a split second longer before swinging, which gives them more time to judge a ball’s path and to make adjustments during the swing. “So, while corking may not allow a batter to hit the ball farther, it may well allow a batter to hit the ball solidly more often,” the researchers write.

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