# In the name of the game.

Several of the more than 750 high school research projects exhibited at this year's fair, May 10 to 16, were inspired by games young investigators play.

* Even if they're unfamiliar with the name, most golfers know the "gear effect" -- the tendency for the head of a golf club to twist subtly as it hits the ball, imparting an unintentional spin. Brian D. Gerardot noticed that when a hammer strikes its target, its head seldom twisted. The reason? The golf club's shaft swings parallel to the head's moving center of gravity, not in line behind it, as the hammer's does. Redesigning a golf club to make it more hammer-like earned the sophomore from Snider High School in Fort Wayne, Ind., a first place "grand award" in engineering.

Gerardot moved the head's center of gravity closer to the shaft by removing most of the body from the head of a metal-and-plastic three-wood club, shaving off some of the toe (point on the head farthest from the shaft) and beefing up the heel (point closest to the shaft). In test "drives," the new design reduced overall torque compared to a conventional three wood and to one with a gear-effect-fighting enlarged head.

However, Gerardot's new design twisted more quickly, exaggerating the effect of its reduced torque. The result: The new club increased the spin on the ball.

Next year, Gerardot hopes to examine another spin-fighting design modification suggested by this year's computer-instrumented experiments. The wood's head has a bulge, a long-standing design feature aimed at compensating for the spin. If the ball contacts the head at a certain spot, however, this bulge actually increases the curve to the right. His data now indicate that a clockwise rotation of the bulge -- "until it's parallel to the shaft" -- should eliminate this.

* Cut a deck of cards and interleave the resulting halves. While a mathematical proof showed that seven such consecutive "riffles" will completely mix up a deck, that's more shuffling than most card players will happily endure, realized inveterate euchre player Aric J. DiPiero, a senior at the Center for the Arts and Sciences in Saginaw, Mich. So he sought -- and found -- a more efficient way to shuffle cards.

Twenty volunteers executed three common shuffling techniques: riffling, overhand (where piles of cards are peeled off the top of a deck and stacked in inverted order), and alternate (adding piles of cards peeled from the top of the deck alternately to the top and bottom of a new stack). After each of 300 such shuffles, DiPiero noted the deck's reordering and used the data to write computer programs simulating 15 different nine-shuffle sequences.

The result? A four-step riffle, riffle, riffle, overhand fully randomizes a deck. Indeed, DiPiero says, "further shuffling will generally be ineffective and may even ... negate some of the effects of the previous four passes." But the overhand must be last or the deck will not become fully shuffled in four steps. Finally, he observes, "the alternating shuffle ... has no apparent utility."

* Since he was 7, J. Paul Tindall has enjoyed tennis. But after practicing his serve, he doesn't enjoy scrambling all over the court to retrieve up to 100 balls. So the 18-year-old senior at Potosi (Mo.) High School has spent much of the last four years developing a radio-controlled Tenni-Runner to collect them, a project that earned him a first place ISEF award from the American Intellectual Property Law Association.

As the three-wheeled, rechargeable-battery-powered device passes over a ball, a pair of rotating paddles shoves the ball up a ramp and into a bin. At 40 pounds, the 11-by-28-inch aluminum-hulled retriever is too heavy for most tennis players to haul around. But Tindall expects that a molded plastic housing for the 150-ball collector -- which he hopes to patent -- should substantially lower its heft and cost.