SCIENCE OF SPORTS: Better Baseball
Baseball players don't know how to hit the ball, says inventor and retired science teacher John Garver. His tips could help baseball players double their batting averages. By applying the rules of physics, Garver has figured out strategies that could radically change the game -- if players will take his advice. Frontiers joins the Kent State baseball team in a series of experiments to test Garver's theories.
Notes & Discussion
Activity 1: Bernoulli's Principle
Activity 2: Demolitions By Bernoulli
Activity 3: Fastball Egg Toss
Report From the Field: John Garver, Inventor
ACTIVITIES: PHYSICS IN ACTION
NOTES & DISCUSSION
- Baseball is not the only sport that illustrates physics phenomena. Consider how different sports -- football, soccer, bobsledding, hockey and others -- demonstrate the concepts of energy, work, friction and inertia. Would knowing the science behind a sport help a person become a better athlete? Why or why not?
- What makes a curve ball curve? The stitches on a ball actually make it curve. The pitcher's fingers hold the ball along a seam, so when the ball is thrown with a snapping motion, it has topspin. Friction provided by the stitches causes a thin layer of air to move around the spinning ball in such a way that air pressure on top of the ball is greater than on the bottom, causing the ball to curve downward -- and the batter to miscalculate the position of the ball.
- The curve ball phenomenon described in the preceding paragraph occurs partly because of the relationship between the pressure of a fluid and its velocity. Does this principle sound familiar? It was determined by 18th-century Swiss scientist and mathematician Daniel Bernoulli and is known as the Bernoulli principle. According to this theory, the faster a fluid moves, the less pressure it exerts. Where do we usually see an application of Bernoulli's principle? (flight aerodynamics)
- How does the Bernoulli principle apply to baseball? A spinning baseball has more air turbulence on top of the ball, producing slower air speed over the ball. Meanwhile, air moving under the ball accelerates and moves faster, producing less pressure on the bottom of the ball. The ball moves downward faster than would normally be expected.
ACTIVITY 1: BERNOULLI'S PRINCIPLE
Try these activities to find out how Bernoulli's principle works and why catchers wear gloves. As you'll see, physics is elementary!
- 2 tennis or ping-pong balls
- masking tape
- Attach one end of a string to a tennis or ping-pong ball with the masking tape.
- Do the same to the other string and ball.
- Hang the balls from a horizontal bar or a dowel rod. Place the balls at the same level and about 3 cm apart.
- Put your mouth between the two balls about two or three inches from them.
- What do you think will happen to the balls when you blow a steady stream of air between them?
- Try it!
- What did you observe?
- Attempt to explain your observation.
ACTIVITY 2: DEMOLITIONS BY BERNOULLI
- one sheet of 8-1/2" x 11" paper
- Draw lines to divide your paper into three sections -- a 2-inch, 7-inch and 2-inch portion.
- Fold your paper along the lines to make a "house" (walls are 2 inches high; flat roof is 7 inches wide).
- Set the "house" on a table.
- What do you predict will happen when you blow hard under the house?
- Try it!
- What did you observe?
- How can you explain your observation?
ACTIVITY 3: FASTBALL EGG TOSS
Why do outfielders and pitchers wear gloves and protective padding? The answer seems obvious, but it's based on a physics principle called momentum and impulse. The momentum an object has is a product of its mass times the velocity with which it is moving (momentum equals mass times velocity). Momentum can be transferred from one object to another. Impulse is the product of a force on an object and the time it takes for the force to be applied (impulse equals force times time). The impulse imparted to an object equals the change in momentum of the object. If the time is increased, force is decreased and vice versa.
When a baseball is caught, the momentum of the moving ball is transferred to the glove. Outfielders and catchers decrease the force of the ball by moving their hand with the ball as they catch it, slowing down the impact. This, along with the padding in the glove, increases the time of impact (impulse), thus decreasing the force with which the ball hits the glove. Protective padding in all sporting equipment and shoes follows this same principle. You can see this phenomenon yourself by trying the Fastball Egg Toss.
- Hold a flat bed sheet at each of the four corners to provide a large target for the pitcher. Make a "pocket" in the bottom of the sheet by holding it up slightly. (You want to prevent the egg from rolling out of the sheet.)
- Throw an egg into the sheet as fast and hard as you can. The object is to break the egg by throwing it into the sheet. (You may want to place the egg in a plastic sandwich bag, just in case.)
- An egg cannot be thrown hard enough into a sheet to break the shell because the sheet, which "gives," transfers the momentum of the egg over a long period of time, greatly decreasing the force on the egg shell.
- Compare what happens when momentum is transferred abruptly. Drop the raw egg (in the plastic bag) on a solid surface. Now, time is very short, making the force much greater.
REPORT FROM THE FIELD: JOHN GARVER, INVENTOR
John Garver holds eight patents for his inventions, which include a Christmas tree ornament and a ball-throwing machine, and he has a secret weapon for any baseball player -- if coaches would only listen.
"Once you make a discovery no one else has made, you want to share it with the world," says Garver. "It takes about 20 years for an idea to get rolling. I just hope I live long enough to see mine used.
"Garver's ideas, seen on Frontiers, could radically change the game of baseball. "If batters use it, they could double their hitting averages." Garver's strategic advice? "I teach players to aim to miss and to take a little more time before they swing. If you teach them to miss, they can bat .500." He adds, "You need an understanding of physics to adapt my system."
Even though the results sound promising, few coaches will listen to him. Yet he continues to promote his ideas tirelessly to coaches in several sports.
Garver's colorful life includes a stint as a pro-tennis player (he turned a tennis-ball throwing machine into one that throws baseballs), a driving teacher (he invented dual brakes used in Ohio), a high school science teacher and part-time engineer. He frequently takes time out from inventing to present programs to the schools, accompanied by one of his "accidental" inventions -- creatures he calls "globs," made of urethane foam that spilled when he was making a tennis racquet, then froze and hardened.
Garver remains optimistic. "The hardest part is getting started. If you fail, so what? I don't know what I'm going to invent tomorrow, but it could make me a million dollars!"
Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.