demonstrations:seesaw_scales
Seesaw Scales
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Simple Machines
Alternative titles: First Class Levers
Summary
Students build a simple seesaw model to explore how levers work. By balancing weights at different distances from a pivot, they learn how effort and load relate through the principle of leverage.
Procedure
- Use sticky tape to secure a binder clip (opened out) to a desk, creating the fulcrum.
- Place a ruler across the binder clip to act as the lever beam.
- Tape a paper cup to each end of the ruler to hold weights.
- Place different weights (such as nuts, marbles, or small masses) in the cups.
- Adjust the ruler’s position on the binder clip until the lever balances.
- Measure and record the distances from the fulcrum to each cup.
- Compare the distances and discuss how they relate to the amount of weight in each cup.
Links
Super Science - June 2023 - Simple Machines - Levers - Seesaw Experiment for K-5 - Massanutten Regional Library:
📄 Seesaw scales - IET: https://education.theiet.org/primary/teaching-resources/seesaw-scales
Variations
- Use different objects for weights, such as coins, stones, or small toys.
- Try using longer or shorter rulers to test how lever length affects balance.
- Set challenges for balancing unusual combinations of weights.
Safety Precautions
- Ensure the binder clip is firmly taped to avoid slipping.
- Handle weights carefully to avoid dropping them on feet or fingers.
- Keep small weights like marbles away from very young children due to choking hazards.
Questions to Consider
- What happens when the heavier weight is moved closer to the fulcrum? (It can balance a lighter weight farther from the fulcrum.)
- Why does the seesaw balance when one side has a smaller weight placed farther from the pivot? (Because the turning effect, or moment, depends on both the weight and its distance from the fulcrum.)
- How do levers make work easier in everyday tools like scissors or nutcrackers? (They increase force or change its direction, reducing the effort needed.)