Airbag:

An airbag is a type of vehicle safety device and is an occupant restraint system. The airbag module is designed to inflate extremely rapidly then quickly deflate during a collision or impact with a surface or a rapid sudden deceleration. It consists of the airbag cushion, a flexible fabric bag, inflation module and impact sensor. The purpose of the airbag is to provide the occupants a soft cushioning and restraint during a crash event to prevent any impact or impact-caused injuries between the flailing occupant and the interior of the vehicle.

Description:

During a crash event, the vehicle's crash sensor(s) provide crucial information to the airbag electronic controller unit (ECU), including collision type, angle, and severity of an impact. Using this information, the airbag electronic controller unit's crash algorithm determines if the crash event meets the criteria for deployment and triggers various firing circuits to deploy one or more airbag modules within the vehicle. Working as a supplemental restraint system to the vehicle's seatbelt systems, airbag module deployments are triggered through a pyrotechnic process that is designed to be used once. Newer side-impact airbag modules consist of compressed air cylinders that are triggered in the event of a side on vehicle impact.

Find out more:

https://www.youtube.com/watch?v=lZhjyP3-lME

https://en.wikipedia.org/wiki/Inertia

https://www.britannica.com/science/inertia