- The Washington Times - Wednesday, January 21, 2004

Bowlers, even if it never crosses their minds, run into Newton’s first law of motion every time they lace up those multicolored shoes. That old saw — an object in motion tends to remain in that state unless an external force is applied — is on display every time a bowling ball crashes through a group of pins.

The sport calls into play a number of physical computations, from the ball’s velocity to how much friction it encounters traveling down the lane.

Even the most rudimentary bowler will impart some kind of “spin” on the ball during the release. Louis Bloomfield, a University of Virginia physics professor, says that wrist twist doesn’t kick in right away, thanks to the fine coating of oil across the lane.

“The ball, when it’s originally released, slides,” Mr. Bloomfield says. “Whatever rotation it’s got, it keeps that for a while.”

He says the ball gradually switches from a sliding state called dynamic friction to static friction — when the skidding ebbs and the ball and lane surfaces begin to make contact.

The amount of friction depends in part upon the mass of the ball and the type of oil in use. Without that oil layer, the friction between ball and lane could generate some heat.

“If the alley weren’t slick enough, there could be burn marks on the alley,” he says.

Once the ball begins rubbing against the alley, it starts moving in the direction of the ball’s spin. The ball possesses two types of momentum during its trek down the lane. The first is velocity momentum, the push from the bowler that starts it down the lane. The second is the angular momentum, the spin that slowly takes over as the ball hurtles down the lane.

Bowling is a game young and old can play, occasionally with similar results. No matter how slowly a child rolls the ball down the lane, if it hits the “pocket” just right — the space between the No. 1 and No. 3 pins for right-handers and the No. 1 and No. 2 pins for lefties — the pins will scatter.

A young bowler doesn’t impart nearly as much energy and momentum as an adult bowler, he says.

“When the pins fall over, they release their own energy,” he says, like a wound spring suddenly let loose. It doesn’t take much energy to knock over a single pin, and if that pin falls just right, a chain reaction can follow.

No matter the ball’s speed or weight, when it hits the pins, the ball’s momentum isn’t lost, it’s partially transferred to the pins. Theoretically, the amount of momentum before contact should be the same as after, except now the pins share some of it.

Older bowlers have another advantage besides speed — they can use a ball much heavier than ones made for younger players.

Bill Wasserberger, director of research and development at Brunswick’s consumer products division in Muskegon, Mich., says a 15- or 16-pound ball brings more momentum and energy than lighter models.

“You get less deflection through the pins at the higher weights,” Mr. Wasserberger says.

Pin action is crucial if a bowler wants a strike. Bowlers need to hit the 1 and 3 pins and have the ball travel through to the 5 and 9 pins while the other pins knock one another over.

“If you hit the head pin dead-on, you don’t get a good enough piece of the 2 or 3 pin,” he says. “You don’t get good pin carry that way.”

Robert Ehrlich, professor of physics at George Mason University, says heavier balls may be the preferred tool of the professional bowler but that speed plays a bigger role in bowling success.

The formula involved in a bowling impact, which calculates how much kinetic energy is involved, multiplies the ball’s mass by the square of its speed, and that product is multiplied by one-half. Because the speed is squared, it takes on a larger role in the overall energy of the impact.

“A rifle bullet has a lot more kinetic energy than a bowling ball,” Mr. Ehrlich says, despite the bowling ball’s greater mass.

David Hagan, a museum scientist with the Science Museum of Virginia in Richmond, says a strike is a perfect example for those looking to understand one of the more compelling areas of physics.

“Bowling is the very essence of collision theory brought to life,” says Mr. Hagan, whose museum has a permanent exhibit dedicated to the theory.

When the ball moves through the pins, its speed slows as some kinetic energy is transferred to the pins in its path.

“It’s called an elastic collision if the two don’t stick together,” he says. “The more springlike the interaction is, the more efficiently that energy is transferred.”

He says after the ball slices through the pins, “you can see how much of its energy [the ball] has, even in a strike. It’s still moving at a huge rate of speed.”

When a large ball smacks into a crush of pins, “the ball can actually send the bowling pins flying at a higher speed than the ball. That’s what allows you to, say, hit two or three pins in a way that cascades to give you the strike.”

Ask any bowler, even a neophyte, and he or she will talk about that perfectly thrown ball that somehow didn’t yield a strike. Physics can explain that, too, says David Schaefer, associate professor of physics at Towson University.

Mr. Schaefer says chaos theory helps explain why it’s so difficult to predict results in bowling. The theory suggests that if even the tiniest of conditions changes in a scenario — such as the pinsetter being slightly off when setting the pins on the alley — the results can be dramatically different from what one might expect.

“It’s very complicated in terms of what’s going to happen,” Mr. Schaefer says. “If you hit the No. 1 pin slightly differently, that can actually cause a huge change in what happens. Its trajectory will be different.”

Mr. Schaefer says it’s good to understand the physics behind everyday activities but that the seasoned bowler uses instinct to draw conclusions.

“They try things and find out what works best,” he says. “They don’t have to understand the friction, but they know how to test it. Most bowlers learn just by trial and error.”