Final answer:
The crumple zone is part of the car designed to absorb the force of impact, functioning by increasing the time over which an impact occurs and thereby reducing the force. Safety features like airbags and padded dashboards also operate under the principle of impulse to protect passengers.
Step-by-step explanation:
The part of the car designed to help absorb the force of impact during a collision is typically referred to as a crumple zone. Crumple zones are designed to crumple and collapse upon impact, which increases the time over which the collision occurs. This is vital because, according to the concept of impulse, an increased time of impact results in a reduced force on the car and its occupants. An understanding of impulse explains how safety features such as airbags and padded dashboards work to protect passengers by distributing the force of impact over a longer period, thus reducing the net force and potential injuries.
In response to the student's multiple-choice question, the correct answer is:
a. It reduces injury to the passengers by increasing the time of impact.
For the quantitative problem about the car's bumper, we can calculate the average force using the formula for work and energy. When a 900-kg car with an initial velocity of 1.1 m/s (equivalent to 4.0 km/h) is brought to rest over a distance of 0.200 m by the bumper, we can use the work-energy principle to find the average force exerted by the bumper.