Physics- What is linear momentum in car air bags?

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bandmanjoe eNotes educator| Certified Educator

Linear momentum is the force created by an object when it moves at a certain velocity.  The formula for calculating linear momentum  is M = m x v, where the M is momentum, m is mass of the object, and v is the velocity the object is traveling.  The force created can be quite large by having either a large mass, a large velocity, or both.  In your question about 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.  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 persons body as they are flying forward.  This cancels the persons momentum and the result is personal injury is greatly decreased.

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