Final answer:
To reduce the force of impact during a head-on collision, prolong the duration of the collision with safety features like airbags and design the vehicle to crumple, which absorbs crash energy.
Step-by-step explanation:
Two factors that can reduce the force of impact during a head-on collision are the duration of the collision and the presence of structures designed to crumple upon impact. The duration of the collision can be increased by features such as airbags and padded dashboards, which slow down the change in momentum by increasing the time over which the force acts on the occupants. This is a result of the concept of impulse, where a longer collision time (Δt) leads to a lower net force (Fnet). Furthermore, vehicles designed to crumple during collisions prolong the impact time and absorb some of the crash energy, reducing the force transmitted to the occupants. This is why racing cars with parts that can crumple have seen a dramatic decrease in fatalities.