Final answer:
Airbags are considered supplemental restraint systems because they provide additional protection to passengers by reducing the force exerted on them in a collision.
Step-by-step explanation:
Airbags are considered supplemental restraint systems because they provide an additional layer of protection to passengers in the event of a collision.
They work by rapidly inflating with gas to create a cushion that absorbs the impact and reduces the force exerted on the passengers. This extended duration of impact helps to minimize the risk of serious injuries, such as head or chest trauma, by spreading out the force over a larger area and increasing the time it takes to come to a stop.