Crash test: why wear a seat belt
Two carts with dummies hit a barrier. The belted one stays put, the unbelted one flies forward.
2D
Age 8+10 min
Momentum & collisionsFriction
Loading simulation…
Press “Run”. Bodies move by the laws of physics: gravity, friction, elasticity.
What the experiment shows
The barrier stops the cart but not the dummy: it keeps moving at the same speed. A belt slows it down together with the car.
How to run it
- Press “Run” and watch both carts.
- Increase the carts’ speed — what happens to the unbelted dummy?
- Find the belt joint and make it longer.
Questions to discuss
- Why buckle up in the back seat too?
- Why is an airbag soft?
The science
Newton’s first law: a body keeps its velocity until a force acts. A belt stretches the stop over tenths of a second, so the force F = m·Δv / Δt is smaller.
Try it at home
Put a toy in a toy car and roll it into a wall — with a thread belt and without.
What to change in the editor
- Make the barrier taller.
- Make the dummy heavier.