What is the total stopping distance for a car moving at 20 mph?

To determine the total stopping distance for a car moving at 20 mph, it is important to consider both the perception/reaction distance and the braking distance. The total stopping distance is the sum of these two distances.

At 20 mph, the perception/reaction distance is the distance the vehicle travels while the driver perceives a need to stop and reacts to that need. This distance is approximately 1.5 feet for every mph, which means at 20 mph, the perception/reaction distance is about 30 feet (20 mph x 1.5 feet/mph).

The braking distance is the distance the car travels after the brakes are applied until it comes to a complete stop. For a car traveling at 20 mph, the braking distance can be calculated using a general formula, which can estimate that at this speed, it typically takes about 20 feet to stop.

Adding these two distances together gives a total stopping distance of approximately 30 feet for perception/reaction plus 12 feet for braking under ideal conditions, which results in a total of around 42 feet.

This is why the total stopping distance is correctly understood to be around 42 feet for a vehicle traveling at 20 mph. This encompasses critical safety information that can significantly impact