# Automobile collision force problem

1. Oct 18, 2009

### mowassel

seat belts and airbags save lives by reducing the forces exerted on the driver and passengers in an automobile collision. cars are designed with a crumple zone in the front of the car. in the event of a 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 witht 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 the decelerates over a distance of only about 5.

a)a 60kg person is in a head on collision. the car's speed at impact is 15m/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 her or she is not restrained by a seat belt or air bag.

c) how do these two forces compare to the person's weight?

2. Oct 18, 2009

### cepheid

Staff Emeritus
What attempts have you made to solve the problem so far? We won't do your homework for you, because that will be of absolutely no help to you. However, if you show us how far you got and where specifically you got stuck, we can help point you in the right direction.

Hint for part (a): how much work has to be done to bring the person to a stop? Over what distance is this work being done?

3. Oct 20, 2009

### mowassel

i tried solving it acouple of time but failed...please or explain how i should do it?