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Collaboration Between Bike Co-op and Physics Department Picks Up Speed

by Lauren Matus

Lead Image: Collaboration between Bike Co-op and Physics Department

AUGUST 19, 2002--People walking into Stephen FitzGerald's classroom encounter a strange sight. Clamped to a tabletop is the back end of a bicycle. A weight hangs from the wheel and a spring balance that is connected to a computer dangles from the pedal. However unusual the apparatus looks, FitzGerald will use it to demonstrate four principles of physics for his Mechanics and Relativity class: conservation of energy, mechanical advantage, equilibrium, and torque.

"I like to use examples that students can relate to what they are doing outside of the lab," says FitzGerald, an assistant professor of physics.

FitzGerald, along with Professor of Physics Dan Styer, has formed a partnership with the Bike Co-op to design bicycles for use in the physics lab. The co-op is one of several Oberlin student organizations that offer memberships not only to students but also to faculty, staff, and townspeople.

"I was trying to redesign some of the labs for this class to make them more accessible to students. One of my research assistants suggested that I contact the Bike Co-op and, after talking to the co-op's directors, this collaboration was born," FitzGerald says. "By having the co-op build our bikes, we can save money and have them made to our specifications. Plus, we can test them before we use them."

Adam Feldman '03 was introduced to the co-op through an ExCo course called Human Powered Machines, which introduced students to the history of the bicycle and taught them basic repair and building techniques. Now the co-op's director, Feldman says that the collaboration with the physics department lives up to the spirit of creativity and empowerment that a co-operative venture provides.

"By collaborating with the Bike Co-op, the College is saving money and forming a relationship within the community," says Feldman.


One question FitzGerald's students will answer during their lab sessions is "what is the advantage of having multiple gears on a bike?"

To answer that question, FitzGerald says he "designed an experiment to calculate the amount of energy that a person uses while riding uphill. Using a weight hanging from the wheel to simulate an uphill climb, students observe what happens when they change gears and measure the amount of force put out using a spring balance. Students are able to calculate how much energy is used by measuring the distance the chain travels on each of the gears and multiplying the total of all the distances by the amount of force exerted on the pedal."

The experiment reveals that although it seems easier to ride uphill in a low gear rather than in a high gear, the two options use the same amount of energy.

"It takes less force to move the chain around a smaller gear," explains FitzGerald, "but in order to move the bicycle you must turn the chain many more times--or in other words, a greater distance, thereby expending the same amount of energy."

With a few simple changes, the bicycle can be used to illustrate the other concepts of physics.

"One reason to use the bikes is the flexibility they offer," says FitzGerald. "Being able to show four different principles with one device continuously challenges students of all levels."

Feldman also considers the project a success.

"We are using scrap parts, so not only is it less expensive for the physics department, but it's a great way to salvage bikes that may otherwise be thrown away," he says. "Besides, it's a great way for the Bike Co-op to advertise."




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