Final answer:
When issued a speed change, one is required to maintain the new speed until either the road conditions or traffic laws indicate a need for a different speed. Understanding the influence of factors like friction and reaction time is crucial for safe driving and compliance with speed regulations.
Step-by-step explanation:
When issued a speed change, you are typically required to maintain that speed until given instruction to do otherwise, such as a new speed limit sign, or until the conditions necessitate a different speed for safety. In the context of driving, you should adhere to the speed specified by traffic signs or by law enforcement. The concept of de jure speed limits represents the legally established limits, while de facto speed limits may refer to the speeds at which enforcement actions are taken by police. It is important to understand that factors like reaction time, the coefficient of friction between the tires and the road, and the overall driving conditions play a crucial role in maintaining a safe speed. For example, in an emergency where you need to apply the brakes suddenly, the distance needed to stop will depend on your initial speed and the road conditions, which is critical to consider to avoid accidents and abide by traffic laws.
Furthermore, the instantaneous speed of a vehicle is the speed at which a car is moving at any given instant, which can be observed on the car's speedometer. On roads, the ideal speed would be the maximum safe speed a vehicle can maintain, particularly while navigating curves, without relying extensively on the tire-road friction. Although some leeway might be given for slight errors in speedometer readings, consistently maintaining the correct speed limit is not only a matter of legal compliance but also one of safety.