Texas Department Of Public Safety Practice Exam

The stopping distance at a speed of 20 miles per hour is calculated by considering both the reaction time and the braking distance. The typical reaction time for a driver is about 1.5 seconds, and during this time, the vehicle will continue to travel forward. At 20 mph, a vehicle travels approximately 29.33 feet per second. Multiplying this speed by the reaction time of 1.5 seconds gives a reaction distance of about 44 feet. Additionally, the braking distance at 20 miles per hour can be estimated using the formula which generally suggests that the braking distance (in feet) is roughly the square of the speed (in miles per hour) divided by 20. For 20 mph, that would be (20^2) / 20, which results in 20 feet of braking distance. Adding together the reaction distance (approximately 44 feet) and the braking distance (approximately 20 feet) results in a total stopping distance of around 64 feet, which is close to the option of 63 feet given. Therefore, 63 feet is the most accurate answer for the total stopping distance at 20 miles per hour, accounting for both the time taken to perceive a hazard and the distance needed to come