A car traveling at 58 km/h hits a bridge abutment. A passenger in the car moves forward a distance of 63 cm (with respect to the road) while being brought to rest by an inflated air bag. What magnitude of force (assumed constant) acts on the passenger's upper torso, which has a mass of 43 kg?

Answer 1

Impulse (force*time) equals momentum change.

Initial velocity Vo = 16.11 m/s
Average velocity while stopping = Vo/2 = 8.055 m/s

Initial momentum of torso = 693 kg*m/s
Time to stop = 0.63 m/Vaverage
= 0.078 s

Average force = (momentum change)/time
= 693/0.078 = ___ N