Physics Demo - Analyzing Angular Inertia of Wheels of Differing Thicknesses

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Physics Demo - Analyzing Angular Inertia of Wheels of Differing Thicknesses In this project/physics lesson, students will be able to test the differences in rotational speed in 3D printed wheels of different densities (infill percentages). By testing the different wheels, students can develop conceptual knowledge about the ways in which differences in mass between the wheels of the same volumes can affect the speed at which it rotates down a ramp. In thinking about introductory demonstrations to introduce new units of study, this project could be integrated into a unit about circular motion, angular momentum, as well as potential energy. The sample 3D STL file included in this project is borrowed from user: timelapse21 https://www.thingiverse.com/thing:1378432 Print Settings Printer: Flashforge 3D Creator Pro Rafts: Doesn't Matter Supports: Doesn't Matter Resolution: .27 Infill: 5%, 25%, 50% Notes: In this print, rafting and supports are not required. The most important part of doing this lesson is the printing of a set of wheels at different infill percentages (5%, 25%, 50%). Post-Printing *Not the quality print, but an idea of what the shape is like when complete* This wheel also includes a rubber band to improve grip onto ramp. How I Designed This For this project, all that is required is the printed wheel, a rubber band to wrap around the wheel, a small ramp (can be a ruler), and something to lean the ramp off of. A stopwatch/recording device is also helpful. Standards NGSS Overview and Background Given the ease of adjusting 3D print densities, the opportunity to introduce a new physics unit/concept, such as angular momentum, can be done using the details of this project. The instructor conducting this demo will print out 3 copies of the same wheel (an example STL is provided) at 3 different infill percentages. By making three separate wheels and testing the angular inertia of each wheel down a ramp, the instructor and work with students to introduce and unpack physical concepts related to circular motion, angular momentum, and potential energy. Since 3D printing allows the instructor greater control over the quality and density of the materials he or she is utilizing in class, there are many opportunities for other manipulatives used in demonstrations and labs to be modified in ways unknown to students to allow for more exploratory growth and encouraging a scientific mindset to explaining scientific phenomena. Objectives Students will evaluate and discuss the differences in the angular inertia of 3D printed wheels of different densities. Audiences Grades (7-12) Ages (12-18) Skills Required *physics knowledge required: kinematics, dynamics, circular motion Subjects Science Physics Skills Learned (Standards) HS-PS2-6 Communicate scientific and technical information about why Obtaining, Evaluating, and Communicating Information Lesson Plan and Activity Step 1: Set up ramp and three different wheels with rubber bands wrapped around them Step 2: Explain what is occurring in the demo and set up recording devices Step 3: Roll down each wheel and record it as it rolls down and off the ramp Step 4: Reexamine the video recording at different speeds (normal, slow, slowest) to observe the differences in angular inertia of each wheel Step 5: Have students determine which wheel has the highest density, medium, lowest Step 6: Discuss why mass might affect the angular inertia of the wheel Step 7: Tie into other learning objectives of the day Materials Needed demonstration space3D printer to make wheels (3)rubber bands (3) to wrap around the circumference of the wheelramp (could use a book, ruler, etc.)camera (smartphone camera can work)timer (if needed) *ruler (if necessary) Skills Learned HS-PS2-6 Duration of Lesson This project will only require about 15 minutes to 30 minutes to conduct. References http://www.nextgenscience.org/dci-arrangement/hs-ps2-motion-and-stability-forces-and-interactions Handouts & Assets None needed. This demonstration is intended to be presented and discusses. Demonstration Example Example video of how the demonstration can be conducted. Taking video of each roll down the ramp can be useful in addition to applying different changes in video speeds to better visualize the effect of increased mass on angular inertia.