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

  1. 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.
  2. Build your ramp by propping one end on a stack of books and securing it with tape.
  3. 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.
  4. Shape a small Play-Doh figure (about 1/2 inch tall) to act as your crash test dummy.
  5. Attach the figure to the hood of the toy car so that it sticks but can come off easily.
  6. Release the car from the top of the ramp and observe what happens when it collides with the pencil.
  7. Discuss the results: the car stops suddenly, but the figure continues moving forward due to inertia.
  8. Repeat the test, this time taping the figure securely to the car with a “seatbelt.”
  9. Observe and discuss how the seatbelt prevents the figure from flying off.
  10. Encourage students to modify the setup—change ramp height, collision distance, or dummy size to test how these affect the results.

📄 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.)