EARTH'S GRAVITY pulled with the expected force in the morning, then loosened its grip in the afternoon.
It was a puzzle for Zafar A. Ismail, a precision-minded physics professor at Daemen College in Amherst. Rather than doubting Isaac Newton's equation, he suspected that the fault lay with the school's lab equipment.
So Ismail linked with Science First, a family-owned company in North Buffalo, to produce his own idea for a gravity measuring device -- one whose internal clock wouldn't be influenced by the afternoon warmth.
"That's what started me on this," said Ismail. Students need 97 percent accuracy for an A in his physics course, and the afternoon classes were struggling. "You could see it as the lab warmed up during the day, the measurements would change."
The result is a $300 device called "Timer 2000" that tracks the speed of a falling object using an infra-red beam, an off-the-shelf Motorola computer chip (designed to monitor auto engines) and a precision-cut metal plate. At its heart is a quartz clock designed to be indifferent to temperature.
"Physics has a bad image (among students), it's perceived to be so difficult," said Raymond Bell, vice president and chief designer at Science First. Seeing equations proven out by real-world experiments "gives students the idea that it's real, that they can start believing in it."
Now entering its second generation, Ismail's device is one of the better sellers for the company, which offers about 50 products aimed at high school and college science classes. Science First was founded in 1960 by Bell's father-in-law, Franklin E. Lee, an accomplished tinkerer, and is headed today by Lee's daughter, president Nancy E. Bell.
At its 11-person shop in North Buffalo, the company assembles science equipment for customers around the world, generating annual sales of $1.2 million. The market for classroom science instruments, governed by its own immutable laws, is now in one of its peaks, Raymond Bell said.
"It all started with Sputnik," he said. The satellite provoked fear of Soviet scientific superiority, and U.S. schools raced to close the knowledge gap into the 1960s. That effort eventually waned, but was rekindled in the mid-1980s when tests showed U.S. students lagging other nations in math and science skills.
Now, a general inclination to invest in education across the board is propelling the company's sales, he said. Ismail's own students include many training to be physical therapists and medical technicians, for whom an understanding of concepts involving force, mass and velocity is basic.
The company's lineup includes the ubiquitous Van de Graaf generator, the metal orb that demonstrates how like charges repel each other by making your hair stand on end.
What sets the Timer 2000 apart in the company's product line is that the idea came from a local scientist.
"This (device) was sort of designed to order," Raymond Bell said. Professor Ismail specified
what the device must do, while Bell obtained the electronics, molded plastic and metal parts that would yield the results.
The key to measuring gravity is tracking the speed of a falling object. With his tower experiment, Galileo demonstrated that earth's pull acted equally on objects with different weights. But to determine the force of the attraction, he would have needed to measure the weights' rate of acceleration.
Ismail's device uses a metal plate with sixteen windows, each 1 centimeter wide. When the plate falls through an infra-red beam, a simple computer takes sixteen measurements of the plate's speed.
With an accurate clock tracking the time it takes each window to cut the beam, the timer can then calculate the falling plate's acceleration -- 32 feet per-second squared.
"That's on earth," Raymond Bell clarifies. "On the moon it would be different."
Gravity at the earth's surface is only one of the aspects of force the timer can measure. Using smaller plates, inclined planes and miniature cars, the device observes Newtonian mechanics in action, measuring acceleration and momentum. The "2000" in the device's name refers to its 2000 memory locations, enabling it to track multiple trials and compute the accuracy of the results. Of course, devices with greater accuracy are used by science and industry, but they tend to be single-purpose instruments costing many times the Timer's $300 price, Ismail said.
Ismail is particularly proud of the Timer's ability to compute the coefficient of friction of a rolling object.
"The value is so small, textbooks say to ignore it," he said. But measuring the slight resistance imparted by the roughness of a rolling surface gives students a greater understanding of the physical world.