# How do airbags reduce injuries?

In a car collision, the driver's body must change speed from a high value to zero. This is true whether or not an airbag is used, so why use an airbag? How does it reduce injuries?

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• markum
Lv 5

Without the airbag, your car hits the wall and stops. Your upper torso continues on for two feet (or so) at the same velocity, according to Newton's First Law. Then your upper torso slams into the dashboard and/or steering wheel, decelerating in just a few inches (with most of those inches due to your head and chest breaking as they absorb the impact)

With the airbag, your car hits the wall and stops. The airbag pops up inches from your upper torso, and you decelerate over two feet (or so), with the airbag absorbing the impact. Final impact with the dashboard and/or steering wheel is much less dramatic.

The airbag greatly increases the deceleration rate and distance, so you experience a fraction of the force felt without the airbag. From a physics point of view, Work = Force * Distance, and the same Work is done in either case.

• watley
Lv 4
4 years ago

Physics Behind Airbags

The air bag extends the time taken to change the speed to 0, so the acceleration is less violent than hitting some part of the vehicle.

It also provides a flexible, increased area of impact to spread the force over more of the body.

It extends the time of the collision reducing the force on your body as;

Force x the change in time = mass x change in velocity

The right hand side is going to change too much. If time goes up, force (on your body) will go down and you'll have broken less bones.

depends on your velocity/speed.. more speed, more impact..

air bags really reduce deaths.. usually, you will come out with a broken limb (arm, leg, etc.)

i would say airbags are really meant to keep death levels lower, but do help reduce injuries too.. also car companies have started installing seatbelts that strain if there is too much pressure at a give time.