2. Devices which are parts of the passive safety system.
Airbags make it possible for passengers to stop more slowly than the car. When the airbag sensor detects a large decelaration, or a sudden stop, the bags inflate in less than a twentieth of a second, giving a much softer impact than the steering wheel would have on the driver.
An airbag will also help a passenger from being thrust forward with as much force as he/she would be without the airbag and so being thrown more slowly means less force and less harm to the person who is involved.