Airbag

[Monty]

The airbag is also called a quot;Supplementary Restraint Systemquot;, and in short it consists of an inflatable bag or envelope which keeps the occupants from hitting any hard parts of the vehicles interior during a crash. In case of a collision, cars equipped with airbags give a much better chance of survival for its occupants, but ONLY when seat belts are worn - hence the quot;supplementaryquot; part.
The way it works is pretty simple in theory: in case of a sudden deceleration (such as a crash) accelerometers within the cars body trigger the ignition of a gas generator propellant to inflate a nylon fabric bag very rapidly (under 1 tenth of a second). The airbag has small vent holes on its side in order to allow the propellant gas to be slowly expelled from it just as the occupant pushes against the bag.
Most airbag equipped vehicles have several accelerometers and/or gyroscopic sensors to help sense various types of impacts. The different signals from these sensors are fed into a microcomputer which can determine the angle of impact and even the severity of the collision taking place. Depending on the result of these calculations, the airbags ECU will decide if the airbag deployment is necessary or not.