Modeling the Dynamics of a Small Catapult to Enhance Undergraduate Studies Article Swipe
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· 2025
· Open Access
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· DOI: https://doi.org/10.18260/1-2-1153-52380
· OA: W2188728441
It is estimated that the average engineering student will work 3000 back of the book style homework problems by the time that they graduate. While these problems can certainly help with the learning process, many do not mimic any type of real world systems that an engineer will encounter in their careers. Furthermore, most do not require the student to develop a physical model of the actual system that they attempt to analyze - this is already done for them in the problem. An example of this can be found in any dynamics book; the work-energy chapter invariably contains problems with springs attached to different slender rods in a variety of different contrived orientations. We have attempted to improve student analytical skills and to provide real world context to the study of rigid body dynamics by creating a catapult project. Students are given rubber bands, catapults, rulers, weights, and a scale. They must determine how to model the arm, the energy stored in the rubber bands (e.g., linear or non-linear springs), and the ensuing projectile motion. Their computations are then tested on launch day - when raw eggs are hurled 20 to 45 feet at a small picture of their instructor. There are a number of different dynamics aspects that can be incorporated into the catapult project. The fixed pin that holds the arm at the bottom can be analyzed using Newton's second law, and a stopper pin that the arm hits can be examined using impulse momentum principles. Students have even analyzed the internal axial stress at a point in the arm as a function of the arm angle as the arm rotates. The catapult project is easy to implement and provides a real world artifact that students must analyze. They make decisions about how to model a true physical system, what effects are negligible (e.g, drag and friction), and what measurements must be taken. We have found this to be a motivational and fun way to help students learn about rigid body dynamics.
