Including reaction time, what is the stopping distance at 20 miles per hour?

The stopping distance at a certain speed includes both the distance covered during the driver's reaction time and the distance it takes to bring the vehicle to a complete stop once the brakes are applied. At 20 miles per hour, the typical reaction time is about 1.5 seconds.

To calculate the reaction distance, you can use the formula:

Reaction Distance = Speed (in feet per second) x Reaction Time.

At 20 miles per hour, the conversion to feet per second involves multiplying by the conversion factor 1.467 (since there are 5280 feet in a mile and 3600 seconds in an hour). Therefore, 20 miles per hour is approximately 29.3 feet per second.

Multiplying by the reaction time of 1.5 seconds gives about 44 feet for the reaction distance.

Next, for the braking distance, a common estimation for vehicles is that at 20 miles per hour, the braking distance is around 25 feet.

Adding these two distances together results in the total stopping distance of approximately 63 feet. This comprehensive understanding of both reaction and braking distance explains why the stopping distance at 20 miles per hour would be correctly identified as 63 feet.