Utah CDL General Knowledge Practice Test

When driving at 55 mph on dry pavement, the total stopping distance you need is influenced by several factors, including perception time, reaction time, and braking distance. At this speed, the average total stopping distance is approximately 400 feet. This distance roughly equates to the length of a football field, which is 300 feet, and takes into account the necessary time to perceive a hazard, react to it, and then come to a complete stop.

Considering the other options, the length of a car is significantly shorter than the distance required, as is the length of a city block and a running track. While various blocks or running tracks can vary in length, none typically exceed or are even close to matching the stopping distance needed at this speed on dry pavement. By understanding that the total stopping distance is around 400 feet, it becomes clear that the length of a football field is the most accurate representation of this requirement when driving at 55 mph.