Final answer:
The formula for stopping distance is Stopping Distance = Breaking Distance + Distance before breaking starts. It is necessary to add the breaking distance and the distance before breaking starts to calculate the total stopping distance.
Step-by-step explanation:
The formula for stopping distance is Stopping Distance = Breaking Distance + Distance before breaking starts. When a driver hits the brakes, it takes some distance for the vehicle to come to a complete stop. This distance is called the breaking distance. Additionally, the distance that the vehicle travels before the driver hits the brakes is called the distance before breaking starts. Therefore, to calculate the total stopping distance, we need to add these two distances together.