Final answer:
Soft barriers on highways work by crumpling upon impact, which increases the time over which the car comes to a stop, thereby reducing the force exerted on the car and its occupants and minimizing injuries.
Step-by-step explanation:
The effectiveness of soft barriers in highway safety can be explained through the physics concept of impulse, which is the product of the net force and the time over which the force is applied. When soft barriers are used, they absorb the impact of a collision, which reduces the peak force experienced by the car and its occupants. These barriers crumple upon impact, elongating the collision time, which, according to the impulse-momentum theorem, results in a lower force over a longer period. Consequently, this reduces the risk of injuries that would occur if the car were to stop abruptly over a short time frame. Therefore, the best explanation is that the soft barriers are designed to crumple upon impact, increasing the time it takes for the car to come to a stop, which reduces the force exerted on it and its occupants and thereby minimizes injuries.
In the case of the given options, option (2) which states that 'The soft barriers are designed to crumple upon impact, increasing the time it takes for the car to come to a stop' is the correct choice because it directly addresses how increasing the time of a collision reduces the force of impact, consistent with the impulse-momentum theorem.