← MAP Physics Lab

Impulse & Crash Safety

Explore how momentum and stopping time affect the force experienced during a collision.

70 kg
15 m/s
Choose a safety scenario
Average force
21.0 kN
Impulse
1050 N·s
A rigid stop happens very quickly, so the force is large.
How safety devices help
1. Increase stopping time
Longer stopping time reduces the force needed to produce the same change in momentum.
2. Increase contact area
Spreading the force over a larger area reduces pressure on the body.
Idealised force–time profile Force (kN) Time (s) 0 30 60 90 120 0 0.1 0.2 0.3 0.4
Key relationship Favg Δt = Δp
Δp = 70 × 15 = 1050 N·s
Favg = 1050 ÷ 0.05 = 21.0 kN
More momentum → larger impulse. Longer stopping time → lower force.
The force–time curve is an idealised visual model. The occupant is assumed to come to rest.