demonstrations:crash_test_dummy
Crash Test Dummy
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Force, Motion
Alternative titles: Investigating Inertia
Summary
This experiment demonstrates inertia, the tendency of an object to resist changes in motion, using a toy car, a small figure made of Play-Doh, and a ramp. When the car crashes, the figure continues moving forward unless restrained by a "seatbelt," illustrating the importance of seatbelts and Newton’s First Law of Motion.
Procedure
- Gather materials: one toy car, Play-Doh (to make a small figure), stack of books or a box, tape, a pencil (to act as a wall), a ruler, and a ramp or piece of cardboard.
- Build your ramp by propping one end on a stack of books and securing it with tape.
- Measure about 10 inches from the bottom of the ramp and tape the pencil across the surface—this is your “brick wall” or collision point.
- Shape a small Play-Doh figure (about 1/2 inch tall) to act as your crash test dummy.
- Attach the figure to the hood of the toy car so that it sticks but can come off easily.
- Release the car from the top of the ramp and observe what happens when it collides with the pencil.
- Discuss the results: the car stops suddenly, but the figure continues moving forward due to inertia.
- Repeat the test, this time taping the figure securely to the car with a “seatbelt.”
- Observe and discuss how the seatbelt prevents the figure from flying off.
- Encourage students to modify the setup—change ramp height, collision distance, or dummy size to test how these affect the results.
Links
📄 Hot Wheels Crash Test Dummy - Stay-at-Home Science: https://stayathomescience.com/2017/03/24/hot-wheels-crash-test-dummy-part-i-inertia/
Variations
- Try using different toy cars or slopes to observe how speed affects the crash.
- Replace the Play-Doh dummy with a small figure made from different materials to see if weight changes the outcome.
- Measure how far the figure travels when unbelted and compare distances under different conditions.
- Use video recording to observe motion in slow motion for analysis.
Safety Precautions
- Conduct the experiment on a flat, stable surface.
- Ensure the ramp is secure and will not collapse during use.
- Keep small materials away from very young children to avoid choking hazards.
- Do not push or throw objects - only release them gently down the ramp.
Questions to Consider
- What happens to the figure when the car suddenly stops? (The figure keeps moving forward due to inertia.)
- What does this experiment show about why seatbelts are important? (Seatbelts provide the force needed to stop your body’s motion safely.)
- What law of motion does this demonstrate? (Newton’s First Law of Motion – the Law of Inertia.)
- How does changing the ramp height affect the figure’s motion? (A steeper ramp increases the car’s speed, so the figure travels farther.)
- What other real-world examples of inertia can you think of? (Passengers lurching forward when a car stops suddenly, or objects sliding on ice.)