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Issue link: https://wardsworld.wardsci.com/i/1517103
Page 2 + ward ' s science DIY Spring Launcher "with a Twist" (continued) Activity Setup: • Each student group (1 – 2 students) will need the student design brief, a 3D printing pen, filament, and a dowel. • To provide a reasonable design constraint and conserve materials, the teacher may wish to cut the filament spools into equal-sized pieces for each student group. • The first time the teacher does this activity, they will need to make one or more simple spring launchers for the competition phase of the lesson. A drilled 2 x 4 block and a matching dowel work well, particularly if the teacher has a jig to drill the holes at precisely the same angle. More complex launchers might include protractors and a pivot joint to allow students to adjust the launch angle. Background Information: To determine the spring constant of their DIY spring, student groups will have to solve the kinematic equation for initial velocity. If the height of the spring launcher is ignored, the range equation can be helpful, as it removes the time variable. d = v2sin2θ rearranges to v = dg g sin2θ The potential energy stored in the spring is equal to its kinetic energy immediately after launch. PE = KE = 1 mv 2 2 Finally, students can calculate the spring constant from the potential energy. PE = 1 kx 2 2 If the elongation distance, x, is held constant for all student groups in this experiment, then the potential energy stored in the spring, and thus how far it flies, is dependent only on the spring constant! More intuitively, the stronger the spring, the farther it flies. Step-by-Step Procedure: 1. Allow time to discuss and design their spring's attributes, such as length, thickness, shape of coils, etc. Students should be able to articulate their strategy in terms of how they plan to create a spring that can store the most potential energy. After introducing the design brief, you are the "guide on the side". 2. Using a 3D printing pen, such as the PIKA3D Pro, students construct their springs. 3. Prior to the spring launching competition, help students make a list of data they will need to collect in order to ultimately determine the spring constant (horizontal range, mass of the spring, launch angle, and elongation length of the spring), and how they will measure each. You may wish to have students perform multiple launches in order to average their data. 4. Provide time and support for students to crunch the numbers. Students should show their work for calculating initial velocity, mechanical energy, and the spring constant. Students should also be able to explain what physical factors affect the spring constant.