Final answer:
The distance traveled before a driver applies brakes is known as the reaction distance, which, along with the braking distance, contributes to the total stopping distance.
Step-by-step explanation:
The distance that a vehicle travels between the time the driver recognizes a problem and the time they apply the brakes is known as the reaction distance. This is combined with the braking distance, which is the distance covered from the time the brakes are applied to the time the vehicle comes to a complete stop, to form the total stopping distance. To calculate the reaction distance, we assume the initial velocity remains constant during the driver's reaction time. For instance, if a car is traveling at 30.0 m/s and the reaction time is 0.500 seconds, then the reaction distance would be the product of speed and reaction time, without any acceleration (reaction = 0).