Final answer:
Cars are designed to crumple upon impact to increase the duration of the collision, which reduces the force experienced by the occupants due to the physics principle of impulse. This design change has led to a decrease in injuries and fatalities.
Step-by-step explanation:
The idea behind modern cars being designed to crumple upon impact is based on the physics concept of impulse and the change in momentum during collisions. When a car crumples, the time over which the collision occurs is increased. According to the impulse-momentum theorem, impulse is the product of the net force acting on an object and the time over which the force acts. This can be expressed mathematically as Δp = Fnet Δt, where Δp is the change in momentum. If the time Δt is increased due to crumpling, for the same change in momentum, the force experienced (Δp/Δt) is lessened. This reduced force translates into less severe injuries for the occupants.
Additionally, plastic components in modern cars contribute to safety by further reducing the weight and leading to better gas mileage. These factors combined have led to a dramatic decrease in fatalities during auto collisions. For example, in car racing, shifting from rigid frames to parts capable of crumpling has significantly reduced deaths.