# What is Airbag? How it works during an accident?

Most of the present Cars has a safety feature called Airbag Do you know what kind of material it is made up of how it works? Let’s begin to know about it.

Airbag traces its origin in mid-1951 by John W. Hetrick, although this become widespread in 1990 in United America and other countries.

Principle: It’s concept based on laws of motion which are given by Newton. We know that moving object has a mass and velocity. They will continue to move until an external force applies to it. Now in terms of Car, We in a Car is like a loose object and continue to move in a moving car during a collision unless we restrain by some force. Seat Belt will restrain our body but our head is free to move. So airbag is focused to work basically on our head.

How Airbag help us?

An airbag is designed to place between passenger and the steering wheel. As the car slows down while obstructing from an object the airbag starts to inflate and automatically deflates as your head presses against it. Deflation is important because if the bag didn’t deflate, our head will bounce back again and again. The basic distance to our seat and Dashboard should be minimum 10 inches so that when an accident occurs we gave enough time for an airbag to inflate well.

An airbag is made up from?

•  Nylon: It is made up of Nylon because it has characteristics of High Melting Point (256 °C/492.8 °F). It is Soft and has a Better sunlight Resistance. This is folded in the dashboard, the seat and the door as a head and knee airbag.
• Sensor: As we know sensor has meant to sense from a distance, so it senses a collision from a particular distance. This collision must be equal to running a brick wall at 16 to 24 km per hour then a mechanical switch is flipped that closes an electrical contact. Now, airbag starts to inflate itself. The accelerometer is a device in it that does this particular task and send this information to sensors. The airbag circuit passes an electric current through a heating element, then this start a chemical explosion
• Nitrogen Gas: In its inflation system there is a reaction of Sodium azide and potassium nitrate to produce Nitrogen gas. Nitrogen inflate the airbag through the Hot blast

NaN3 + KNO3 = N2 + Na2O + K2O

What is Inside inflation system?
The inflation system has a solid propellant and an igniter. This starts a Chemical reaction which produces NO2
• Solid Propellant: Airbag system ignites a solid propellant, this burns fastly to create a large volume of gas. The gas burst with a speed of 200mph or 322kph, it is faster than our eye blink. This also dissipates the bag through tiny holes so that we can move when we are taking to the hospital.
• Talcum Powder: The powdery substance released from the airbag to keep the bag lubricated when it is in the storage.

In recent, every car has an inbuilt feature of AIrbag due to our safety concern but that does not mean now seat belt is not mandatory we should wear a seat belt first.