Final answer:
A common rule for maintaining distance between commercial motor vehicles on the highway is the 3-second gap, ensuring sufficient time for reaction and vehicle stopping, given the various driving conditions.
Step-by-step explanation:
The question about the distance that must be maintained between commercial motor vehicles traveling in the same direction on a highway requires an understanding of safety, stopping distances, and reaction times relying on principles of physics. The correct distance can vary based on speed, road conditions, and vehicle weight, but a common rule of thumb is to maintain at least a 3-second gap between vehicles. This allows the following driver to have an adequate distance to stop if necessary, taking into account the time needed for the driver to react and the vehicle to come to a stop.
To elaborate with a practical example, Bridget has observed from her classroom window that cars take roughly 3 seconds to cover the distance between two poles that are 50 meters apart on a straight stretch of road. This observation aids in realizing that the 3-second rule is not just a random number, but one that corresponds to the time it might take a vehicle to cover a noticeable distance under normal driving conditions.
Considering the stopping distance and reaction time as shown in FIGURE 2.34, a quick reaction time of 0.500 seconds does not significantly alter the total stopping distance, reinforcing the merit of the 3-second rule. This time interval gives the following vehicle enough space to react and safely stop if the lead vehicle suddenly slows down or stops.