demonstrations:second_class_levers
Second Class Levers
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: Wheelbarrow Lever Demonstration
Summary
Students use a ruler, a stack of books, and a finger fulcrum to model a class two lever. By placing a load at different points on the lever, they observe how load position affects the effort required to lift it.
Procedure
- Stack several books vertically to create a support base.
- Place one end of a ruler on top of the books to act as the fulcrum.
- Use your pointer finger to lift the other end of the ruler, providing the effort.
- Place a weight at the point on the ruler closest to your finger (the effort) and try lifting. Note how heavy it feels.
- Move the weight to the middle of the ruler between the fulcrum and the effort. Lift again and observe.
- Place the weight closest to the fulcrum and lift once more. Compare how heavy it feels compared to the other positions.
Links
📄 The Lever Experiment - eSchoolToday: https://eschooltoday.com/learn/class-two-lever-experiment/
📄 Lifting with a Lever - Science Buddies: https://www.sciencebuddies.org/Files/789/4/Classroom_Activity_Teacher_Levers.pdf
Variations
- Try using different weights to see if the effect is more noticeable.
- Swap the ruler for a longer or shorter lever and compare results.
- Replace the pile of books with a block, cup, or small box as the fulcrum.
Safety Precautions
- Ensure the pile of books is stable to prevent the ruler from slipping.
- Use a weight that is not too heavy to avoid dropping it on fingers or toes.
- Supervise younger children to prevent pinched fingers under the ruler.
Questions to Consider
- Which load position required the least effort to lift? (Closest to the fulcrum.)
- Which load position required the most effort to lift? (Closest to the effort.)
- Why does placing the load near the fulcrum make it easier to lift? (Because it reduces the turning effect, giving the lever a greater mechanical advantage.)
- How does this experiment relate to real tools like a wheelbarrow? (The closer the load is to the wheel/fulcrum, the easier it is to lift and move.)