Plan the investigation
What students will do
Start with a guided comparison, then plan an investigation, analyze a graph, and check a prediction.
- Compare rider masses. Keep rider distances equal and observe rotation direction for different right-side masses.
- Design and collect. Choose at least five right rider masses. Adjust right rider distance to find balance with the left rider unchanged.
- Linearize the results. Transform mass and balance-distance data to make a straight line. Use the fit to infer the left rider’s distance.
- Explain and predict. Explain the opposing torques, then predict and test a balancing distance for an unused right rider mass.
What students will learn
- Connect force and lever arm with torque.
- Use observed rotation to identify a balance condition.
- Test an inverse relationship in rotational equilibrium.
Common misconception
Must the heavier rider’s side rotate downward?
The lever arm matters along with the rider’s weight.