'Hidden' Wheels - Conservation of Angular Momentum Lab

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Hidden Wheels - Conservation of Angular Momentum Lab In this project/physics lesson, students will test the differences in angular momentum of two different disks with varying placements of masses. By testing wheels at different angular velocities/momenta, students can develop conceptual and experimental knowledge about how mass placement affects speed and momentum. This lab activity can be integrated into a unit on circular motion, angular momentum, and potential energy. It is also suitable for AP Physics I classes. Print Settings Printer Brand: MakerBot Printer Model: MakerBot Replicator 2 Rafts: Yes Supports: No Resolution: 0.20 Infill: 15% Notes: Each print should be fine at 0.20 resolution, though 0.10 would produce a finer wheel with better holes for screws. Infill at 15% works well as the hidden masses of small metal beads won't break through the plastic cover. Rafting can help with levelness, but it's not necessary. Standards NGSS Overview and Background This lesson tests the concepts of conservation of angular momentum in a 2D space. The instructor should print out enough copies of each wheel and lids for each group. After printing, the instructor should distribute small, equal masses into each opening and seal each wheel, ensuring each group gets one of each type. After distributing the wheels, the instructor should help students set up a ramp to roll their wheels down. Ideal angles are 30, 45, or 60 degrees, which can be recorded for data. Students should record time, distance, and mass, using these quantities to calculate velocity and later angular momentum. Objectives Students will evaluate and discuss the differences in the angular inertia of 3D printed wheels with different densities. Audiences Grades: 7-12 Ages: 12-18 Skills Required *Physics knowledge required: kinematics, dynamics, circular motion* Conservation of Angular Momentum Equation: L=mv⊥r Subjects Science Physics Skills Learned (Standards) HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion describes HS-PS2-2. Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system. Lesson Plan and Activity Step 1: 3D Print all necessary wheels for lesson/lab activity Step 2: Equally distribute materials and wheels to all groups Step 3: Instruct students about how to engage in lab activity and record data Step 4: Monitor data collection and calculations that students are doing for velocity and angular momentum Step 5: Allow students to discuss/answer conceptual questions regarding the difference in data collected from one wheel to the other (they should not know of the 3D model the wheels are based on) Step 6: Class should convene and discuss results Step 7: Reveal the 'secret' to the differences in angular momentum! Materials Needed *Demonstration/lab space *3D printer to make wheels *Small bead-like weights (steel balls, nuts, screws - preferably small, dense items) *Small screws (machine screws preferred, nuts not necessary) *Ramp (could use books or small plastic/wooden boards) *Timer *Rulers/tape measures *Handouts/lab worksheets (to supplement lesson)