Final answer:
The maximum lawful speed limit on state highways depends on the location and is usually clearly posted on signs. De jure speed limits are the official speeds to follow, while the de facto speed limit might consider the actual behavior that triggers enforcement. Conversions, such as 100 km/h to 62 mph, help understand the equivalence of speed limits in different units.
Step-by-step explanation:
The answer to the student's question cannot be provided without a specific jurisdiction because laws and speed limits vary by location. However, I can give a general description about understanding speed limits. On state highways, the maximum lawful speed limit is usually posted through a speed limit sign. When we talk about highway speed regulations, we might refer to both the de jure speed limit, which is the official speed stated on road signs, and the de facto speed limit, which might be the speed that enforcement officers begin to issue traffic citations. For example, on some interstates, the speed limit might be set close to 60 mph (27 m/s or 96 km/h), which is a common speed limit in many regions, though this can vary.
From a conversion standpoint, 100 km/h is equivalent to approximately 62 mph, since 1 mile equals about 1.609 kilometers. Meanwhile, 80 km/h converts to about 49.7 mph or 22.2 meters per second. These conversions are useful for understanding the relationship between the different units of speed measurement used around the world.