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UA professor examines science of baseball


Arizona Daily Wildcat

UA professor Terry Bahill takes a swing through his "bat-chooser" machine Monday afternoon in an engineering lab. The machine calculates the batter's swing speed and helps players to find the most effective bat weight.

By Blake Smith
Arizona Daily Wildcat,
March 1, 2000
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Many professional baseball players have long contended that hitting home runs is as much of a science as a physical skill.

Now, a University of Arizona professor has found a way for baseball players to hit more of them.

UA systems and industrial engineering professor Terry Bahill has examined the physical aspects of baseball, from the way batters perceive pitches to how the weight of the bat can drastically affect the speed of a ball.

Bahill found that a pitch is naturally broken into thirds by a batter. The first part of the pitch is sensory gathering, the second is computing how fast the ball is traveling and when to swing, and the third is the actual swing.

Batters often complain that a fastball "jumps" as it crosses the plate, causing them to swing under the ball, but Bahill contends that defies the laws of physics.

"When the batter starts to swing, he takes his eyes off the ball to look at the predicted bat-ball collision point," he stated in a news release. "When the ball comes back into his view, it is higher than his mental model predicted, and he sees it 'jump' higher than where he calculated that it would be."

Bahill contends the way to solve the problem is not to change the psychological process of the batter, but to change the weight of the bat.

"We're talking about momentum here," he said, while showing off the collection of weighted bats in his laboratory.

Bahill said his main objective has been to determine how the weight of a bat affects the speed of bat-to-ball contact.

Bahill operates a "bat chooser" machine in his engineering lab.

The simple machine consists of two bars. The lower bar has two laser beams set at a standard distance apart from each other, while a string dangles from the upper bar.

The player swings through the machine, attempting to hit the string. A computer attached to the laser beams records the time it takes for the bat to travel from one laser beam to the other and calculates the swing speed.

Different weights of bats are used by the batter, and then, a graph is created to find a balance between greatest bat weight and fastest swing speed, Bahill said.

For instance, a player can hit a ball with a whiffleball stick - low weight, but fast speed - and never hit a home run. On the other hand, when hitting a ball with a bat made of solid lead, the weight of the bat would be great and the swing speed would be hampered drastically, Bahill said.

The purpose of the bat chooser machine is to find the best bat for each individual hitter, he added.

Bahill also studied the advantages of aluminum bats over wooden bats.

A misconception is that aluminum bats generate higher bat-to-ball speeds, which could endanger the safety of a pitcher, Bahill said.

He disproved the theory by looking at basic tendencies of baseball players.

"To go from an aluminum bat of one length to a wooden bat of the same length, the weight of the bat will have to increase," Bahill added.

Bat speed then decreases because of the increased weight. That increased weight overcomes the speed deficit, giving the ball more momentum. Hence, the ball travels faster to the pitcher.

Bahill is now examining the effects of an end-loaded bat - with weight shifted from the mid-section of the bat to the end - on a batter's bat-to-ball collision speed.

The theory is that momentum will increase because of the weighted end, causing the batter to hit the ball with greater force, Bahill said.

Since 1987, Bahill has worked with the UA softball team to help them determine the best bat weight for each player.

"I recommended that they use 25 ounce bats, but the lightest bats they had were 31 ounces. I checked back with them a few years later and come to find out they had 26 ounce bats," he said.

UA softball player Nicole Giordano used Bahill's "bat chooser" machine last semester.

"What he recommended helped some," said Giordano, a junior centerfielder. "I'm getting more distance on the ball this year, but I think it's more mental and not so much the bat."

This spring, Bahill hopes to test his findings on Chicago White Sox first baseman Frank Thomas. Thomas is not his first choice, however.

"Mark McGwire would be ideal," he said.

According to Bahill, the St. Louis Cardinals' first baseman is interested in the science of baseball but fears that altering his bat weight - and in turn his swing speed - might change his record-high home run production.

Currently, Bahill is beginning a study on the vibrations of a bat after making contact with the baseball.

To this point, his studies have focused on how to make the hitter better. Now, he will look at how to make the bat better.

While Bahill studies all aspects of baseball in the lab, he said the only time he watches the sport is when his children have it on the television.

"I'm not a baseball fan," he said. "I'm just trying to figure out the science behind it."

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