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The Marshmallow Trebuchet

Picture of The Marshmallow Trebuchet
Introduction

For my Physics 123 class, each team was to come up with a group project somehow related to physics in which we would research a topic, build something to perform experiments with (optional), write a paper, and present our project to the class at the end of the quarter. We decided on building a trebuchet small enough that we could fire it in a fairly large lecture hall. But what to use for projectiles? We needed something that wouldn't hurt any one or damage school property if errant shots when flying where they weren't supposed to. We quickly settled on marshmallows over a lunch meeting. They are light and soft, two properties not typically found in projectiles so it would be a good challenge to see how far we could hurl them. We set out a goal to launch them 20-30 feet, assigned roles to team members, and turned in our project proposal which was quickly approved. 

My part of the project was the design, fabricate, and build portion. Other team members were tasked with researching the history and present day uses of the trebuchet and to make an attempt at working out the physics and math of the trebuchet. The math proved to be one of the most difficult aspects of the project since there is a whipping action where the fixed end of the whip is moving through an arc path while the sling accelerates through it's own path. 

This instructable will focus on our design selection and the actual design we built. 
 
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herkavar1 year ago
I feel a nice warm glow that I'm not the only one who saw ldvance's design and thought a phi based cam would do the trick. Here are some launches with my little phi-buchet from just over a year ago:https://www.youtube.com/watch?v=YekYbcxi7OU

This managed to launch a rubber ball, about the size of a golf ball, 330 feet down range with a peak altitude of about 160 feet.
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