Final answer:
At 50 mph, you should follow the 3-second rule for a safe distance, which translates to approximately 13 car lengths, considering the average car length to be 16.5 feet.
Step-by-step explanation:
At a speed of 50 mph, the number of car lengths you should stay behind the vehicle in front of you is generally determined by the 3-second rule, which is considered a safe following distance. The exact number of car lengths can vary, but a car length is typically around 15 to 20 feet long. If we consider the average car length to be roughly 16.5 feet (5 meters), and if you're driving at 50 mph (which is equivalent to approximately 73 feet per second), following the 3-second rule would require you to be at least 219 feet behind the vehicle in front of you. This would equate to approximately 13 car lengths, ensuring that you have sufficient space to stop in case of sudden halting.