Riviet said:
I remember this part of the preliminary course, it's in the motion topic with improving the safety of cars, e.g seatbelts and airbags.
oh okay prelim., i remember now. It was stuff to do with inertia and momentum/impulse..I found some of those notes:
Safety Devices:
5.2.1 Inertia is an objects tendency to remain at rest or uniform motion unless acted upon by an external force, as governed by Newton’s First Law of Motion; this applies to all things including vehicles.
5.2.2 Newton’s First Law of Motion is not apparent in many real world situations such as normal driving because there are many factors that are involved and external forces contributing. Forces like air resistance stop vehicles traveling at uniform motion so inertia is not seen.
5.2.3 Low speed zones are well justified phenomena in built-up areas because of stopping distances that cars take. A car traveling only a little faster down the road takes a LOT longer to stop further up the road, with pedestrians crossing and cars pulling out of parked spaces it’s only reasonable to have low speed zones. Air bags also are justified as the forces acting upon a person’s body in a collision are enormous and enough to kill the person if devices like air bags and crumple zones were not installed, these devices increase the time over which a force acts and in every collision there will be an impulse (Impulse = Ft) but if the time interval is increased that will therefore decrease the force felt. Crumple zones assist in the change of momentum which all helps to maximize chances of driver survival.
5.2.4 Air bags and seatbelts have been introduced in ALL cars in Australia now and are proving very successful in reducing driver fatalities, seatbelts restraining passengers to stop them flying through the window screen and ensuring they make contact with the airbag correctly are saving lives every day. Airbags that inflate then deflate cushioning drivers (and even passengers) from the full force encountered in a collision are exceptionally reliable as they work off sensors measuring seriousness of collisions and deciding whether or not airbags should be deployed. Seat belt’s stretching ability puts it right next to airbags the supplementary restraint as they both reduce the net force acting on the driver and are proven to reduce fatalities on our roads.