Final answer:
The minimum distance you must be able to see in all directions before turning around on curves and hills is typically 500 feet. This distance accounts for the time needed to recognize hazards and safely maneuver the vehicle. While the eye's acuity plays a role in visibility, traffic rules are designed for safety and might differ from the scientific resolving power of the eye.
Step-by-step explanation:
When considering the minimum distance you must be able to see in all directions before turning around on curves and hills, traffic safety rules typically state that you should have a clear view of at least 500 feet. This allows for sufficient time to recognize any potential hazards, such as oncoming vehicles, and to react accordingly. Additionally, it's important to take into account factors like the speed of your vehicle, the speed of oncoming traffic, weather conditions, and visibility.
The eye's acuity is another factor to consider when determining distances for safety on the road. While questions from physics concerning the resolving power of the eye due to diffraction by the pupil provide insight into how far one might be able to resolve two headlights on a car, they do not directly translate to traffic safety rules. Traffic rules regarding minimum visibility for safe turning are designed with overall public safety in mind and incorporate a variety of factors.