During a head on collision between two automobiles, the occupants are decelerated rapidly. Use the idea of work to explain why a air bag that quickly inflates in front of an occupant reduces the likelihood of injury.

The work done to stop a car during collision is described in the equation W = F * d where F is the force of collision and d is the distance of impact. In this case, when work is constant and the distance is long, then the force must decrease. If the distance shortens, then the force of collision must increase. The inflation deflation process of the airbag lengthens the distance, hence force is lessened.