How many meters does it take to brake at forty kilometers per hour?

[Gomes]

Braking at forty kilometers per hour requires 5 meters. It is recommended to maintain a safe following distance while driving. A safe following distance refers to the necessary gap that a trailing vehicle maintains with the vehicle ahead to avoid accidental collisions. Keeping a safe following distance is the most direct, effective, widespread, and fundamental method to prevent rear-end collisions. Theoretical Basis: According to the laws of mechanics, a vehicle continues to move forward for a certain distance during the time it takes to come to a complete stop from motion. If the vehicle is too close to the one in front, it is highly likely to collide with it, causing a rear-end accident. To ensure that the trailing vehicle does not collide with the leading vehicle under any extreme circumstances, the trailing vehicle must always maintain a certain distance from the leading one, allowing sufficient braking space (including braking time and braking distance) in case of emergencies. Measurement Criteria: There is no absolute standard for a safe following distance, only dynamic criteria. The most direct and significant factor affecting the safe following distance is the vehicle's speed. As the speed increases, the required braking force, braking distance, and the distance covered at the original speed during the reaction time also increase accordingly. Maintaining a safe following distance requires controlling the vehicle's speed.