Each year for the past 30 years, physics students at South Tama County High School compile all of the physics concepts that they have learned throughout the year and challenge themselves to the ultimate test. Provided with 15 pieces of two-foot long balsa wood (a very lightweight wood used mainly for making models), one-half ounce of hobby tacky glue, and various cutting, sanding, and clamping tools, students are instructed to build a wooden bridge that can withstand the weight of a bucket plus additional pounds of sand.
Advised by physics teacher Paula Neyens, 32 students began crafting their bridges on Monday, Feb. 24, and ended on Thursday, March 6. The first step of the building process was to design a blueprint to be followed while building the bridges. Students had to have a completed blueprint before receiving supplies. As the judges scored on how well the bridge matched the blueprint, students couldn't alter their designs after completing the blueprint.
After students presented a finished blueprint, they received their supplies and got to work. With 30-45 minutes a day, plus extra optional time before and after school, most students had no trouble completing their bridges on schedule.
Hailee Weiss with physics teacher Paula Neyens.
The guidelines that students were to follow while constructing their bridges were very strict. The bridge cannot go over a 30-35 cm length, 6-7.5 cm width, and 10 cm maximum height. No arches or laminating was allowed. Students were also not allowed to alter the wood in any way: no soaking in water, wire insertion, painting, etc. All construction was to be done in the physics classroom and only if a teacher was present.
"This is the 30th year I have had my students do some kind of bridge project. The first time we did this we used toothpicks. A few years later we tried uncooked spaghetti. Each year I make some changes in the design, supplies, dimensions, or something. Displays are optional now but they were required at one point," said Neyens.
Many students chose to design a display to present their bridges in a more creative way to the judges, even though a display was not required or included in the grading process. This year, students have created mini versions of beaches, Candyland board game, a Dora the Explorer scene, a zoo, a farm complete with horses and cattle, and a Jurassic Park inspired dinosaur enclosure. Junior Robert Tyynismaa won the display award with a very detailed Lego-land scene.
Though the display was an eye-catcher for the audience and judges, the ultimate test was whose bridge could hold the most weight. After being judged on March 10 and 12 with classmates present, senior Yanet Merino won with the highest efficiency of 773 times her bridge's weight, followed by Angel Escarzaga with 750, Maddie Nelson with 661, and Taylen Anderson with an honorary mention. As most of the bridges averaged around 0.020 pounds, students' efficiencies were determined by dividing the pounds the bridge was able to withstand by the weight of the bridge.
Merino might have won this year, but the standing champion of the bridge building contest was Josh Smith, class of 2002, who constructed a bridge out of balsa wood that held 86 pounds. However, the strongest bridge ever, made out of toothpicks, was built by Chris Simon, class of 1987. Three people were able to stand on a 2x4 on top of the toothpick bridge without it breaking, according to Neyens.
"This project is a good way to show physics in action. I like to see how the students problem solve and figure out how to fix things that go wrong," said Neyens. "I hope they think about forces and how those forces are transferred and spread out, but honestly I think most of them just build a bridge and hope for the best."