- The Washington Times - Thursday, March 14, 2002

Baseball pitcher Kenny Beck knows there is a science to his sport. Beck, the relief pitcher for the University of Maryland in College Park, says that although he isn't a physicist he realizes there are scientific principles behind the game he plays. "I'm sure the coaching we receive lends itself toward placing your body in a position where science is in your favor, but they don't approach it with scientific terms," Beck says. "The coaches and physicists address the same things in different ways."
America's favorite pastime is based on physics, says William Parke, chairman of the physics department at George Washington University in Northwest. Everything from the type of pitch and the construction of the baseball to the swing of the batter and the flight of the baseball can be explained in scientific terms.
Mr. Parke says that every time a pitcher takes the mound the player has a choice of how to throw the ball. A fastball thrown by a major league pitcher usually travels at least 90 miles per hour, covering the distance from the mound to the plate in about less than half a second. It rolls off the fingers of the player with a backward spin, tending to rise, with about 1,600 revolutions per minute.
Pitching the ball at an angle causes a curveball, Mr. Parke says. A slider, which spins horizontally, moves left and right. It is thrown like a football pass, with the wrist cocked at a 90-degree angle. If a player puts a forward spin on the ball, it drops faster and is called a screwball. A knuckleball has no spin at all.
The stitches on the ball affect the movement of a pitch, Mr. Parke says. Major league regulations require the ball to have exactly 108 stitches sewn on its cowhide cover. Inside the leather, 110 feet of wool yarn encases a rubber ball, which holds a cork ball. The ball must be 8 inches in circumference.
"The surface of the ball is not smooth, so it won't move through the air straight," he says. "The stitches generate turbulence through the air as it spins."

Alan Nathan, professor of physics at the University of Illinois at Urbana-Champaign, says most pitchers overlook the role of gravity when they throw balls from the pitcher's mound. Gravity is the natural force of attraction exerted by the Earth, which draws objects at its surface toward the center of its body. Due to gravity, the baseball drops about three feet from the time it leaves the pitcher's hand and arrives at home plate. For that reason, the pitcher's mound, which is 60 feet, 6 inches from home plate, is elevated.
"If the pitcher's mound was level with home plate, it would be harder for the pitcher to throw consistent strikes," Mr. Nathan says. "Players intuitively know how to take into account gravity."
He says momentum plays a major role in the collision between the ball and the bat. Momentum is a measure of the motion of an object, which is equal to the product of its mass and speed. The bat, which travels about 70 miles per hour in the hands of a major league player, weighs about 30 ounces, though that can vary from player to player. It has more momentum than a 5-ounce baseball that travels 90 miles per hour.
"It's like colliding a car with a train," Mr. Nathan says. "The car is going to bounce a long way, and the train is barely affected."
If a ball comes into home plate at about 90 mph and leaves at about 90 mph, Mr. Nathan says, the change in momentum is about twice the initial momentum. The batter has to stop the ball, and then force it forward. The ball absorbs about 75 percent of the energy, leaving only about 25 percent to propel the ball forward.
"The time over which the force of the bat acts is very short, about 1/1000 of a second," he says. "You need a lot of force to give you the change in momentum. The peak force is about 9,000 pounds."
Terry Crowley, batting instructor for the Baltimore Orioles, says he tells his players that bat speed is one of the most important factors when hitting a home run. With a player who has the physical strength to hit home runs, Crowley advises him to make contact with the ball in front of home plate.
"Bat speed is at its maximum at that point," Crowley says. "With someone who hits singles or doubles, I tell him to let the ball come to him a little more and go with the pitch."

Although Crowley gives his players this instruction, he does not believe there is a scientific formula for success in hitting home runs. He says there are many components that affect the outcome of the hit, such as hand-eye coordination and the ability to handle pressure. Players of all sizes and styles of hitting have been successful at hitting home runs.
"Hitting is complex," he says. "There are many human factors in hitting a baseball."
Larry Noble, professor of kinesiology at Kansas State University in Manhattan, Kan., who specializes in biomechanics, says that when a batter hits the ball, he wants to transfer the energy as efficiently as possible by hitting the "sweet spot" in the bat, which minimizes the number of vibrations that travel through the bat or the hands of the batter.
To find this area, which is different for every bat, take the bat and hold it at the end of the nub. Take a hammer and begin tapping and find the spot where it doesn't produce vibrations in the hand. This area will differ for every bat because some bats are longer than others.
Mr. Noble says fast-pitch softball players usually use stiffer, metal bats because they don't hit the "sweet spot" as often as slow-pitch softball players and major league baseball players. Stiff metal bats allow fewer vibrations to travel to the hands when the "sweet spot" is missed. More flexible wooden or metal bats store a greater amount of energy during the swing that is released during the impact on the "sweet spot."
"If the bat is flexible and you hit the sweet spot, better things happen," Mr. Noble says. "But if you don't hit the sweet spot, then you are better off having a stiff bat because you have less of a penalty if you don't hit the sweet spot."

Thomas Humphrey, senior scientist at the Exploratorium, a science and art museum in San Francisco, says that when a baseball leaves a bat, the optimum angle for a home run is about 35 degrees. The Exploratorium maintains a Web site dedicated to the science behind baseball at www.exploratorium.edu/baseball/index.html.
The angle of the ball is important because not only does it have to sail across the distance of the field, but it needs to make it over the fence. If a ball is angled too much, it will be a fly ball and probably will be caught by an outfielder. If the ball comes off the bottom of the bat, it will be a ground ball, which is usually an easy out.
"Batters don't do calculations when they are swinging," Mr. Humphrey says. "They just swing as hard as they can."
The main property of aerodynamics that affects the ball's flight is the density of the air, Mr. Humphrey says. If the air is dense, the ball needs more energy to push aside its molecules. This takes more energy, and the ball usually travels a shorter distance. The density of the air decreases as temperatures and altitudes increase.
"It's easier to hit a home run in Denver's Mile High Stadium than in San Francisco," Mr. Humphrey says. "The elevation is higher and the air is less dense."
This principle affects even the most successful players, Mr. Humphrey says, such as San Francisco Giants hitter Barry Bonds, who hit 73 home runs last season, which marked the 567th of his career. Despite San Francisco's denser air, Bonds broke Mark McGwire's single-season record set in 1998 of 70 homers.
Mr. Humphrey says baseball is not the only sport that scientists study. Tennis and golf involve scientific principles, which are similiar to baseball because they use a ball that bounces against a surface. Like baseball bats, tennis rackets and golf clubs have changed as technology developed. Skiing and hockey also have been studied extensively.
"Some athletes have worked with physicists to try to understand their performance," he says. "Other athletes learn through coaches and trial and error."


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