Final answer:
Air bags are designed to be used alongside seat belts to provide optimal protection by distributing collision forces over a longer time, thus reducing the impact on occupants.
Step-by-step explanation:
Air bags are designed to be used with seat belts as another safety device. When used in conjunction, air bags and seat belts provide comprehensive protection in the event of a collision. The air bags deploy upon impact, providing a cushion that helps to distribute the forces experienced by the passengers over a larger area and over a longer period of time, thus reducing the risk of serious injury. They allow the net force on the occupants to act over a much longer time when there is a sudden stop. This is based on the principle of impulse, where reducing the force can be achieved by extending the time over which the momentum change occurs. A seat belt restrains the occupant and works together with the airbag to ensure that the safety systems function effectively.