Johns Hopkins Gazette | December 15, 2008
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The newspaper of The Johns Hopkins University December 15, 2008 | Vol. 38 No. 15
Batteries NOT Required in Student-Engineered Cars

Stephanie Sobczak lines up El Monstruo while teammates John Falzon and Vincent Rolin look on. The group's car made it to the semifinals.
Photo by Will Kirk / HIPS

Freshman teams turn to the power of rubber bands and mousetraps

By Phil Sneiderman

For their first major design project, freshman mechanical engineers at Johns Hopkins had to think low-tech. The students were assigned to design, build and race model cars that could not use conventional motors — or even a single battery. Each vehicle could be powered only by two mousetraps and six rubber bands.

Last week, in a hallway of the Computational Science and Engineering Building on the Homewood campus, 20 student teams put their motley car creations to the test. Many of the vehicles boasted bodies made of wood slabs, wheels made of DVDs and other parts made of balsa and foam board. The challenge for each car: traverse an 11-foot-long curved course while maneuvering around two soda bottles filled with sand. The requirements to win: accuracy and speed. The prize: bragging rights and a good grade.

When the checkered flag descended, the winners were Michael Rizzoni, Nick Salzman and Alex Strachen, the three students who built and raced a vehicle called Awesom-O. Supervising the event was course instructor Allison Okamura, an associate professor of mechanical engineering. The competition, she said, was more than an entertaining exercise. While working on their cars, the students learned about design approaches, potential and kinetic energy, friction, prototyping methods and other topics relevant to mechanical engineering.

One of the key challenges was designing the self-propelled vehicles to turn their wheels and travel around the two slalom course obstacles. Some students, including the winners, solved this problem by mounting rods atop their vehicles. The rods bumped the obstacles and forced the front wheels to steer the cars around the bottles. Yet another solution was a special mechanism designed to switch the steering angle depending on how far the vehicle traveled.

The best-designed vehicles veered around these obstacles and cruised over the finish line. Other entries performed less successfully, running out of power just inches from the starting line or slamming into one of the obstacles.

In an added nonengineering twist, the cars were required to use a pen, paintbrush or other implement to mark a pattern on the white paper covering the hallway floor. These machine-made markings will be included in the exhibition We're Not Alone at the Mattin Center March 23 to April 12, part of the Art on Purpose project called Everyone an Artist? Exploring the Meaning of Being an Artist.

To watch a video from the event, go to:


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