Final answer:
To avoid a rear-end collision, you should maintain at least a three-second following distance between your vehicle and the one ahead. This time increases in poor conditions or when following larger vehicles. Safety and the ability to react to sudden stops are the primary reasons why this distance is crucial.
Step-by-step explanation:
To avoid causing a rear-end collision, it is recommended to maintain an adequate following distance between your vehicle and the one in front of you. There are various rules about the following distance, and one common guideline is the three-second rule. This rule states that a driver should stay at least three seconds behind any vehicle that is directly in front of the driver's vehicle. To estimate this distance, when the rear of the vehicle ahead of you passes a stationary object like a sign or a tree, you should be able to count to three before your vehicle passes the same object. If you pass the object before you finish counting to three, you are following too closely.
The three-second rule provides a minimum cushion for drivers to react and avoid collisions in good weather and road conditions. However, if road conditions are poor, such as in heavy rain, fog, or ice, it is wise to increase this distance to ensure safety. It is also important to remember that larger vehicles, like trucks and buses, require more stopping distance, so when following these types of vehicles, a greater following distance should be maintained to ensure safety.
The question about how far away a car must be before it might be safe to cross and how many car lengths this distance equates to is similar in context but depends on multiple factors such as the car's speed, the observer's walking speed, and visibility. A general rule of thumb is that if a car is driving toward you and it is 28 meters away, roughly the length of eight cars, it might be safe to walk across the road, but only if you are certain that you can complete the crossing well before the vehicle's arrival. Always prioritize safety and err on the side of caution when judging distances and crossing roads.