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Crash test physics
Intermediate
Crumple zones extend collision time to reduce force.
Crumple zones, seat belts and airbags extend the stopping time and spread the force. Using impulse: F_avg = mΔv/Δt.
A 1500 kg car at 15 m/s stops in 0.1 s with 225 kN; in 0.3 s only 75 kN.
Rigid cars aren't safer.
In more detail
Crash test physics uses impulse, momentum and energy to predict how a vehicle and occupants behave in a collision. Designers aim to extend the stopping time and absorb energy safely.
Real-world uses
- Crash test laboratories measure forces on dummies using accelerometers.
- Car makers design crumple zones to absorb kinetic energy.
- Car manufacturers design crumple zones so the car takes longer to stop, reducing the peak force on the occupants.
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Frequently asked questions
Why do crash tests matter?
They measure forces and injuries, which guide design of seatbelts, airbags and structures.
What is the most important factor?
Stopping time: the longer the time, the lower the average force on the occupants.
Why are stiff cars dangerous?
A stiff car stops in a shorter time, so the average force on the people inside is much larger.
Related topics in Momentum & Collisions
Momentum of light · Radiation pressure · Momentum in fluids · Sports impulse examples · Momentum and kinetic energy relation · Hamiltonian momentum