Seat belts and air bags save lives by reducing the forces exerted on the driver and passengers in an?

Question

automobile collision. Cars are designed with a “crumple zone” in the front of the car. In the event of an impact, the passenger compartment decelerates over a distance of about 1 m as the front of the car crumples. An occupant restrained by seat belts and air bags decelerates with the car. By contrast, an unrestrained occupant keeps moving forward with no loss of speed (Newton’s first law!) until hitting the dashboard or windshield. These are unyielding surfaces, and the unfortunate occupant then decelerates over a distance of only about 5 mm.

A) A 60 kg person is in a head-on collision. The car’s speed at impact is 15 m/s. Estimate the net force on the person if he or she is wearing a seat belt and if the air bag deploys.
B) Estimate the net force that ultimately stops the person if he or she is not restrained by a seat belt or air bag.
C) How do these two forces compare to the person’s weight?

Please show your work. Thanks.

Answer 1

I won't do your homework for you, but you should look here:
http://hyperphysics.phy-astr.gsu.edu/hbase/carcr.html#cc1

Good luck. :)

Answer 2

The crumple zone, seat belts, and the air bags are all for the reduction of force exerted towards a passenger in case of accidents. This has something to do with impulse which is defined to be momentum over time. Force and impulse are related to each other. Impulse is a force and you could check this by looking at their units which are both in kg-m/s2. The crumple zone, seat belts, and the air bags are all used to increase time or lengthen the collision time before hitting the driver since time is inversely proportional with the impulse, that is, the longer the time, the lower the force exerted.