Physics of Cheating in Baseball

[tachyonbb]

The June 2011 issue of the American Journal of Physics has an article titled: "Corked bats, juiced balls and humidors, The physics of cheating in baseball".

Alan Nathan from U of Illinois, Lloyd Smith from Washington State and Dan Russell from Kettering University are the authors.

They corked a bat and tested its coefficient of restitution and discovered that a corked bat has no advantage when compared to a normal bat.

They tested baseball's from the 1970's (from Charles Finley estate). American League balls by Rawlings and signed by MacPhail. They compared these to Rawlings balls made in 2004. They also reviewed the tests done in 1998-2000 and those done by the Cleveland Plain Dealer. Bottom line was that there was no significant difference in the coefficient of restitution with the different baseballs. The limited number of samples to test made any definitive statement impossible.

The last test was using the humidor like the one used at Coors field. They concluded that the humidor is effective in reducing the distance a baseball will fly.

I have provided a synopsis of the article. If you want more details let me know. The article is online but you have to have a subscription to view the article.

[alanu]

I wonder how they tested the corked bat.

If they used the same swing speed I would imagine it wouldn't help much, but my understanding is that the way the corked bat works is that it makes the bat lighter to improve swing speed.

[tachyonbb]

They did increase the velocity of the bat for the corked bat. The velocity was higher, but the mass of the bat was less which pretty much cancelled the effect of the higher velocity.

The corked bat did not have a better Coefficient of Restitution when compared to the original bat. There is no "trampoline" effect from the corked bat like there was with college metal bats. More bat speed but less mass resulted in the corked bat performance being a little less than the original bat.

One other possibility that the authors mentioned is that with the lighter bat the hitter could wait longer on the pitch before committing to swing. "That is, in the parlance of baseball the batter can "get around quicker", allowing the batter to wait longer on the pitch as well as more easily adjust the swing after the swing has already begun"
"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."

[steve B]

I don't buy their ideas about the corked bat. I can see where it wouldn't have any effect at the same speed, but increasing the bat speed has to have a positive effect. Kinetic energy is half the mass times velocity squared.
So you'd have to have a very large change in mass to offset a decent change in bat speed.

Did they test with actual pro caliber players swinging? There's a huge difference between what they can do and the rest of us. Personally I use as heavy a bat as I can find because my hands will only move so fast. I've played with a couple people who had some real athletic ability and they both used very light bats, and couldn't hit as well with mine. One guy hit a limited flight softball pitched slow pitch roughly 350ft! the bat was something like 31oz, almost a little league bat. And he didn't finish college ball.(Had to choose baseball or enginering and chose engineering, but we all know the odds...)

Steve B