This year our homeschool group put together a Science Olympiad team for the first time. We were competing in the 4th to 6th grade division.
Our task was to design a car power completely by a mousetrap that would go EXACTLY 10 meters. Every mm short OR long of 10 m would result in points. Teams also gave a time estimate for completing a run. Points were given for the difference between predicted time and actual time. Keeping the centerline of the track between the wheels was worth a -20 point bonus. The goal was to have the LEAST number of points.
The boys came up with an original design that works quite well. The chaise is made entirely of LEGO Technic pieces. The drive wheels are CD’s with LEGO pieces taped to them to allow for attachment to the axles. Balloons increase the friction on the cds to prevent spinning. The final design uses florist wire to attach the mousetrap to the chaise. A K’nex rod is taped to mousetrap as an extension rod. The final design used the wheels shown, but without the tires.
THE GOOD NEWS:
This mousetrap car was quite capable of going more than 10 m.
THE BAD NEWS:
After a lot of trials on different flooring surfaces the boys thought they had the right distance figured out. For some reason their results at the competition didn’t match what they had the day before.
Adjustments to the pull string length seemed the most reliable way of adjusting the travel distance. A shorter pull string traveled shorter distances.
We tried a braking system, but our design was hard to set and tangled too easily.
I was really pleased that the boys came up with a design that was completely original. It made the project a lot more fun and interesting.
Using LEGO pieces limited the axle length. A larger width would have made it easier to earn the centerline bonus, but their design did earn the centerline bonus on one of its two runs.
Almost all the cars at the competition used the same design, a rectangle of basswood with four cd wheels and threaded axles. They used a longer extension arm that was pinned down when the mousetrap was set. The result was they could leave the string attached to the axle and self brake.