Physics+behind+Car+collision+damage+reduction+devices

=Physics Behind Car collision damage reduction devices=



**__Seatbelts__**

The physics behind a seatbelt is based on the concept that the passenger’s inertia is different from that of the car. Hence the seatbelt serves to protect the passenger by preventing him fromout of his seat and crashing into the windshield by absorbing his inertia upon impact. The design of the seatbelt to have different components (i.e. shoulder belt, safety belt, lap belt etc.) allows the pressure against the passenger to be balanced, preventing excessive pressure that could cause injury on a specific part of the body.


 * __Airbags__**

Also known as a supplementary restraint system (SRS) or supplementary inflatable restraint (SIR), with the word “supplementary” suggesting that the airbag is an addition to seatbelts as a safety precaution, not as a replacement.



1) The car crashes, causing immediate and drastic deceleration.

2) An accelerometer (an electronic chip that measures acceleration) detects the change of speed in (1).

3) An extremely drastic deceleration would trigger the airbag circuit (normal braking does not satisfy the requirements for this to happen).

4) The electric circuit passes an electric current through a heating element.

5) The heating element ignites an airbag propellant made of sodium azide.

6) Sodium azide, being a fast burning fuel, would produce large amounts of nitrogen gas that is filtered into the nylon airbag.

7) The expanding airbag then blows off the plastic cover on the steering wheel and inflates in front of the driver.

8) The driver, upon the crash impact, pushes against the airbag that has small holes around it, causing the gas within to escape.

The airbag serves to protect the driver’s head, neck and chest areas, and is deflated after use to allow the driver to leave the car. The airbag is inadequate for driver safety without the seatbelt, and the use of the seatbelt and airbag can completely eliminate the possibility of an injury, even in severe car crashes.


 * __Crumple Zones__**

-is a structural feature designed to compress during a car collision in order to reduce the impact caused on the occupants of the car. -usually found at the front and the back of the vehicle. -Crumple zones work by absorbing the energy created from the impact of the crash, preventing it from being directly transmitted to the occupants or intrusion, deformation of the passenger cabin. When the car is on the move, they have inertia which means that they will want to continue forwards with that direction and speed (Newton's first law of motion). when there is a sudden deceleration of the vehicle due to impact, the occupants will continue forwards at their previous speed due to inertia, and impact the vehicle interior, with a force equivalent to many times their normal weight due to gravity. The purpose of crumple zones is to slow down the collision and to absorb energy, to reduce the difference in speeds between the car and its occupants.