Plan the investigation
What students will do
Start with a guided comparison, then plan an investigation, analyze a graph, and check a prediction.
- Compare impact offsets. Keep incoming mass and velocity fixed. Compare rotation after central hits and hits on opposite sides of the pivot.
- Design and collect. Choose at least five incoming masses. Keep impact offset and launch velocity fixed and read angular velocity after sticking.
- Linearize the results. Transform mass and final angular velocity data. Use the fitted model to determine the fixed disk’s rotational inertia.
- Explain and predict. Apply angular-momentum conservation about the fixed pivot, then predict and test an unused incoming mass.
What students will learn
- Connect impact offset with signed angular momentum.
- Choose a reference point for conservation-law reasoning.
- Infer rotational inertia from collision data.
Common misconception
Must a central hit make the fixed disk spin?
Linear momentum alone does not determine angular momentum about the pivot; the impact offset matters.