The Trebuchet: A Study of Mechanics and Motion

Overview

Objectives/Goals My project was to evaluate how different sling lengths and counterweight masses affect the distance a trebuchet throws a ball. My hypothesis was that a trebuchet would shoot farther with a medium sling length and a medium counterweight. Methods/Materials Initially, I built a 6' trebuchet. My manipulated variables were the length of the sling and the mass of the counterweight. I used 4 different sling lengths: 36", 33", 30" and 27". I used three counterweights: a 4"x12" PVC pipe filled to the top with sand, filled half-way and empty. I tested each counterweight with each sling length 5 times. I then averaged the 5 trials to obtain a distance measure. Results I discovered that with a full counterweight and a 27" sling length the trebuchet shot the farthest. In other words, the heaviest counterweight with the shortest sling worked the best. Conclusions/Discussion My results did not support my hypothesis. After I did my testing, I learned that the counterweight was the principle energy for firing the projectile. The heavier the weight the more force it had, the farther the ball flew. I also learned that the distance between the fulcrum and the counterweight and also the sling length were important. The shorter the distance, the faster and farther the ball flew as well.

Competition history

• CSEF 2005 Applied Mechanics/ Structures & Mechanisms/ Manufacturing · Entry J0202

Resources

• CSEF project summary ↗

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