Final answer:
The 'second crash' in a vehicle collision is the impact experienced by the vehicle's occupants, which occurs when they hit the interior of the car or are restrained by safety devices. Safety features like airbags and crumple zones are crucial as they increase the time of impact, thus reducing the forces experienced by the individuals.
Step-by-step explanation:
Understanding the Second Crash in Vehicle Collisions
When discussing vehicle collisions, the term 'second crash' refers to the impact that the occupants of the vehicle experience after the initial collision. It occurs when the driver and passenger(s) hit the steering wheel, instrument panel, or windshield. This is an important safety consideration because even after the car itself has stopped moving, people inside the car are still in motion until they hit something or are restrained.
The impulse delivered during a collision is the product of the force applied and the time over which the force acts (Fnet Δt). Extending the time over which the occupants come to a stop significantly reduces the force they experience. This is why safety features like airbags and crumple zones are vital; they increase the collision time, thus reducing the force on the car's occupants. The inclusion of these safety mechanisms can mean the difference between life and death or major injury. Answering a common question, it is option 'a' that explains how crumple zones protect passengers: It reduces injury to the passengers by increasing the time of impact.