Physics of Airbags!

Airbags are used in automobiles because they are able to minimize the effect of the force on an object involved in a collision. Air bags accomplish this by extending the time required to stop the momentum of the driver and passenger. When encountering a car collision, the driver and passenger tend to keep moving in accord with Newton's first law. Their motion carries them towards a windshield that results in a large force exerted over a short time in order to stop their momentum. If instead of hitting the windshield, the driver and passenger hit an airbag, then the time duration of the impact is increased. When hitting an object with some give such as an airbag, the time duration might be increased by a factor of 100. Increasing the time by a factor of 100 will result in a decrease in force by a factor of 100.

Linear momentum is the force created by an object when it moves at a certain velocity.  The formula for calculating linear momentum is p = m x v, where the p is momentum, m is mass of the object, and v is the velocity the object is traveling.  The force created can be large by having either a large mass, a large velocity, or both. In terms of a car airbag, you want to create a force that is sufficient to counteract the momentum of a human body moving forward due to inertia.  When the car is involved in an accident, inertia keeps the human body moving forward. Before the use of airbags, people were relegated to the old philosophy "Grab something and hang on", which wasn't too much help in avoiding personal injury. Many statistics show the massive number of deaths during accidents when times were using that philosophy. Airbags don't have much mass, but they are deployed with a large velocity, inflating in less than a second, which absorbs the momentum of the person's body as they are flying forward.  This cancels the person's momentum and the result is personal injury is greatly decreased.