Class at Eight and Battle at Ten: Physics Students Build Trebuchets


Kayla Goldenberg

How do you make physics fun? In Dec. and Jan., HBHA juniors and seniors built trebuchets to showcase what they have learned on paper in physics.

The physics students preparing to fire their trebuchets. Photo credits: Jane Martin

Physics is offered every other year, and for the past 6 years honors physics teacher and upper school principal Todd Clauer facilitated the project with Science Department Chair, Cody Welton. The project, begun in 2007 by former HBHA teacher Dr. Larry Mckenna, continues to exist as a fundamental unit in both the physics and honors physics course curriculum.

A trebuchet is a medieval war weapon that is designed with a throwing arm with weights on it. When the arm is released, it can fling a variety of objects into the air at a great distance.

“The trebuchet project is an engineering design project where students in physics learn how to design, build, and use a medieval siege weapon in a competition format and as a team,” says Clauer. He emphasizes that this project “is meant to stretch students to think, ‘How do I build something that does what I want it to do?’”

Initially, students built one-foot models of trebuchets from a kit format to understand how the machine operates and which measurements and ratios produce the most efficient machine. Once they have that basic introduction, students were taught how to handle power tools such as saws and drills, and they designed and built their own trebuchets from scratch in teams of three or four. Teams were given wood wheels, etc. but they had to assemble the machines themselves. Students had to determine the details of their machine in this process, which involved determining measurements of the wood, sling, hook, and an optimal angle at which the machine would launch.

Following weeks of preparation, students trekked out into the bitter cold to launch their trebuchets in a competition. There were five teams, each with a unique design for their personalized trebuchets. All the trebuchets were lined up on the soccer field and launched one after another in three rounds. The trebuchet that launched its projectile the farthest would win the competition.

One of the teams watching their trebuchet in action. Photo credits: Jane Martin

While this process seems straightforward, there was a lot more to it than meets the eye. When preparing for launch, teams altered their machines to produce more consistent, powerful launches.

“Creating the sling is the most difficult part in my opinion,” says Clauer. “It was what most teams had trouble with and was left up to a lot of trial and error.”

In the end, the results did come down to the sling. Juniors, Jacob Bell, Nina Gale, Jonathan Mehari, and Amanda Sokol, readjusted their sling more than any other group, and their trebuchet wound up shooting the farthest.

“Being winners in the end made all the trial and error and struggling worth it,” says Mehari. “It was just really great to have the support of my teammates throughout the process as well as the rest of the class.”

The trebuchet project is one example of all the unique hands-on experiential learning HBHA offers. Designing, building, and launching medieval war weapons is not the kind of assignment students are accustomed to receiving, but at HBHA, this is a project that students are intrigued by and look forward to.