Ward's World Activity Guides

+ ward ' s science Page 4 DIY Spring Launcher Design Brief Objective: Your team must design and produce a small plastic spring to be used as a projectile in a distance competition. You must characterize your spring in terms of its spring constant, stored potential energy, and initial velocity after launch in a distance competition. Design Specifications: 1. Your spring must be constructed of PLA plastic and must be constructed using a 3D printing pen. 2. You and your partner will be provided with a pre-cut piece of PLA filament. No additional material of any kind may be part of your constructed spring. 3. Your spring may be any length, but its inner diameter must not be smaller than the diameter of the dowel used for launching. 4. When launching your spring, its total length must not exceed the length of the launching dowel. Additional Constraints: • You must characterize your spring in terms of its spring constant (N/m), potential energy at launch (J), and muzzle velocity (m/s). • Teams must consist of not more than three (3) students. Students must construct and characterize their springs in teams, but they must complete the performance tasks individually. • Projectiles are dangerous. Safety glasses must be worn at all times, NO exceptions. Springs must NEVER be launched toward any person. • Timeframe: • No more than 20 minutes will be given to discuss and decide on your design. Be sure to consider as many physical parameters as possible — such as length, diameter, and thickness of coils. • No more than 20 minutes will be given for constructing your spring using the 3D printing pen. During this time you may test launch your spring in a designated area as many times as you like, but be aware that DIY polymer springs may be less durable than manufactured metal springs. No additional filament will be provided if your spring breaks. • At the end of the design and construction your spring will be impounded and the launch competition will commence. Spring Characterization: Teams may collect additional data using any equipment available in the physics classroom, including but not limited to: metric rulers, tape measures, protractors, electronic balances, spring scales, motion sensors, photogates, stopwatches, etc. However, calculations of the spring's initial velocity, potential energy, and spring constant should be based on the spring's performance during the launch. You will neglect any air resistance, rotation, or harmonic motion that results from the launch. • Correct determination of spring's minimum initial launch velocity (35%) • Correct determination of spring's minimum potential energy before launch (25%) • Correct application of Hooke's Law to determine the spring constant (25%) • Written explanation of the physical factors affecting a spring's spring constant (15%)

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