Each year, 8th Graders at Fieldston Middle cap off a physics unit related to motion by designing and building cars powered by mousetraps. The project culminates in the mousetrap car race, where the entire 8th Grade gathers in the Varsity Gym to test their creations. Here, two students, Adriano W. ’26 and Sophia T. ’26, share their reflections on the project and the exciting day at the races.
On Friday 4/8, we wound up our mousetrap race cars as excitement buzzed in the Varsity Gym. We spent the last two weeks taping, gluing, and drilling in an attempt to optimize our cars for this exciting day. When starting the process, a crucial choice had to be made: Would we prioritize speed, distance, or design? Most teams prioritized distance, while only a few focused on design, and speed fell somewhere in between.
To build the mousetrap car, we started by constructing a basic car consisting of a body, two axles, and four (or fewer) wheels. Then we glued a mousetrap to the body of the makeshift car, with a rod extending out from the original mousetrap mechanism. We attached a string to the rod, and when this string was spooled on the axle opposite to the rod, the mousetrap would gradually be dragged backwards, increasing the potential energy of the system. When the axle was finally released, the potential energy was converted into kinetic energy, turning the wheels in the process. The rate at which this energy was converted was dependent on the length of the aforementioned rod attachment, so a distance car benefited from a longer rod, while a speed car benefited from a shorter one.
On the day of the race, after several smaller heats to determine who was worthy of the final rounds, the much awaited finals arrived. The distance race was very exciting but was fairly obvious in terms of the winner. However, the winning car was unfortunately trampled by a crowd of spectators before it could realize its full potential. The speed race also appeared to be rather one-sided, but it was very difficult to see as nearly everyone in the gym had crowded to witness the much-anticipated race. Finally, the design votes were counted, with “Lightning McQueen” coming in first place, having built a car quite reminiscent of its popular Pixar namesake.
The mousetrap car project was one that many had been looking forward to for weeks. It was an amazing way to wrap up our physics unit, incorporating everything that we learned about Newton's laws of motion, momentum, and energy. Two weeks ago, we divided into groups of two to four people, and were given basic materials: one mousetrap, washers, zip ties, CD’s, axles, fishing wire, wood, and cardboard. We were also free to find our own materials that we wanted to use from home as well, and groups got very creative with their designs. Groups built and designed their mousetrap cars, testing them along the way in order to improve and make adjustments as necessary. The cars were generally either built for speed or distance, with speed cars being very lightweight and small, and distance cars being much heavier and longer.
On the day of the race, all of the cars were lined up in the middle of the Varsity Gym. As we waited for the races to begin, I was amazed at how many different designs people had come up with, and how creative and innovative groups were with the materials they used. Everyone walked around with a slip of paper in their hands in order to cast their vote for the “People’s Choice Award,” the grade’s choice for the best-designed car. After voting, my group took our car over to the start of the distance race. We designed our car for distance, using records as the back wheels, and a long but thin frame in order to create a longer car. As we were winding up our mousetrap, it snapped! We rushed over to Mr. Baglio, who showed us how to make a quick fix to the spring by pushing it down and adding some tape to stabilize it. As my group and I rushed back over to the start of the distance race, we were nervous our car might not perform as well as it usually did, due to its injury. To our surprise, we won our heat! After all of the races concluded, the winners of each heat for distance and for speed went over to their races. As we lined up for the final race, we were nervous, but excited to show off all the hard work we put into our car. We let go of our car, and off it went, slowly but surely. At last it came to a halt, and we were in second place! My team was so excited, and it was the highlight of an amazing afternoon.