Pedal power: Teaching physics through energy-makin

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Joined: Nov 20 2007, 02:03 PM

Jun 18 2012, 05:02 PM #1

Pedal power: Teaching physics through energy-making bicycle
Santa Cruz Sentinel

Last modified: 2012-06-18T12:11:01Z
Published: Monday, Jun. 18, 2012 - 5:10 am

APTOS, Calif. -- The $600 contraption drills home some basic laws of physics, and the importance of energy conservation, but also provides a way for students to get some light exercise.

In August 2008, Cabrillo College in Aptos, Calif., received a five-year grant from the National Science Foundation to create a series of programs aimed at getting more students to pursue careers in math and the sciences. Last year, some of that grant money was used to create an "energy bike," which provides a stark, visual demonstration of just how much more energy is required to light an incandescent light bulb compared with its fluorescent counterpart.

"It is a wonderful educational tool to connect a student in a very kinetic way to understanding energy demands of different appliances and energy transfer," Susan Tappero, a math instructor and director of the MESA (Math, Engineering, Science Achievement) program, wrote in an email.

A group of Cabrillo students worked for about seven months to build the bike, whose parts alone cost about $600. They mounted an old bicycle onto a wooden platform, then attached a 12-volt motor and electrical cord to the rear wheel.

The other end of the cord is plugged into an outlet installed on the top of a wooden box, surrounded by two rows of incandescent and fluorescent light bulbs. An inverter inside the box transforms the energy, and the entire bank of fluorescent lights up with virtually no pedal effort required. But getting even one incandescent bulb to light up takes considerably more effort, like switching from fifth gear to first gear on a regular bicycle.

"You just don't get that (kind of understanding) over a table of numbers," Tappero said.

In addition to building the bike, the students also created a handbook with step-by-step instructions so others can build their own. To view a demonstration of how an energy bike works, go to

Last week, the bicycle was donated to Joe Manildi, who's taught physics at Aptos High School since 2005. In the fall, he plans to use the bike as a teaching tool for students in his classes, but it also will be available for use in other classrooms and school districts throughout the county.

Though the energy bike will be used as a classroom tool, it also can be used, at least in theory, to power everything from a small, old-style television set to cell phone chargers. Eventually, Manildi said, he hopes to have his own students create their own, using the one Cabrillo donated as a model.

"Whenever we talk about energy and power, we can take it out and have a real demonstration, because energy can be a pretty abstract concept," he said.

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