Question

How do inertia, acceleration and momentum impact on an airbag?

Answer 1

First inertia makes driver (when suddenly stops his car) keep him moving with the velocity of the car.
Air bag will push his face applying force oppose the direction of velocity making him to deceleration.
f*t = Impulse = change in momentum =m delta v,so air bag is air not solid so that the time taken will be high in order to make a huge change in momentum and driver slows down to stop his motion.