Final answer:
At a speed of 50 mph, the recommended following distance is approximately 15 car lengths, based on the three-second rule and an average car length of about 4.5 meters.
Step-by-step explanation:
The question of how many car lengths one should stay behind the vehicle in front at a speed of 50 mph refers to safe following distances while driving. A common recommendation is the "three-second rule", which suggests that a driver should stay far enough behind the car in front to allow for a full three seconds to pass before reaching the same spot. Considering an average car length of about 4.5 meters (15 feet), and assuming a car travels at approximately 22.35 meters per second at 50 mph, the three-second distance would be roughly 67.05 meters (220 feet). Therefore, following distance at 50 mph would be about 15 car lengths, given the average car length. When braking, factors affecting stopping distance include the car's speed, the conditions of the road, and the vehicle's braking capabilities.