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what is an air bag ? How Do Airbags Work

what is an air bag ?

It is a device that is designed for the safety of the persons in the car when met with an accident in an unnoticeable way. It consists of a flexible fabric type of bag usually known as air cushion. The air bag is designed in such a way that it expands with in the completion of tenth of a second, with the impact of the vehicle. Now a days we see air bags in most of the cars as the safety becomes the first preference to all the buyers. It is expanded quickly even in the times of sudden deceleration.

how do airbags work


Working of an Air Bag-

An Air Bag contains a chemical that helps to expands the gas in it. Nan3, Sodium Azide is the chemical component that is present in the air bag. This is the heart of the air bag.

  1. When a car is met with an accident, air bags open.
  2. At the first nano second of the incident, due to inertia the body in the car tends to move even after the accident. So, the energy is sniffed by the sensors in the car which monitor the air bags
  3. The sensors are directly connected to an ignitor which generates heat.
  4. The generated heat causes the chemical reaction to decompose Sodium Azide to Sodium metal and Nitrogen gas.
  5. The process completes with in a blink of an eye.

6.This gas fills the air bag made of fabric completely making it to appear at the steering as well as in other places of the car.

The below equation describes exactly the working of an air bag and the chemical reaction that takes place in an air bag.

NaN3 –> 2 Na + 3 N2


NaN3 = Sodium Azide.

Na = Sodium

N2 = Nitrogen


There may be a question saying the quantity of Sodium Azide present in the car. This is a astonishing fact to everyone. A normal man’s fist can hold about 130 grams of sodium azide. This 130 grams can produce about 67 liters of Nitrogen. I think this is much further than I think is usually enough to inflate a fabric air bag.


Now coming to the energy transfer, the sensors detect the amount of collision. After evaluating the crash or impact of collision, the air bags come into work. The energy of the person in the car is completely absorbed by the air bags. So the passenger cannot move further.


The air bags are known as Supplemental Restrain Systems as it projects passengers in the car. They can be related to seat belts as it also one of the safety ensuring devices.

There are different types of air bags considering the position and area they are placed. They are as follows-

  1. Seat belt air bag
  2. Frontal air bag
  3. side torso air bag
  4. side tubular air bag
  5. Knee air bag
  6. Rear curtain air bag
  7. Sear cushion
  8. Center air bag


These are also used in aerospace and military applications. Air crafts which are in a problem of flight can deploy air bags at the time they meet the ground or surface to enhance the smooth landing of the craft with no problems.



  1. The air bags can be used only once.
  2. Once they are used, they need to be replaced.
  3. They cannot secure the person after the first impact when there is a following impact.
  4. It has no use in multiple collisions.
  5. They may cause to stop the functioning of the brain with major head trauma with delayed inflation of air bags.

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