What comprises a vehicle's stopping distance?

The stopping distance of a vehicle is defined as the total distance it takes for a vehicle to come to a complete stop after the driver has identified the need to stop. This total distance includes two key components: reaction distance and braking distance.

Reaction distance refers to the distance a vehicle travels from the moment a driver perceives a hazard until the driver physically applies the brakes. This is influenced by the driver’s reaction time and the speed of the vehicle at the time the brakes are engaged.

Braking distance is the distance that the vehicle travels while the brakes are being applied until it comes to a complete stop. This distance is affected by several factors, including the vehicle's speed, road conditions, tire conditions, and braking efficiency.

By combining both reaction distance and braking distance, one arrives at the full stopping distance a vehicle requires to safely come to a halt in response to a sudden need to stop. Thus, the correct answer reflects the understanding that stopping distance is the sum of both reaction distance and braking distance, which is critical for safe driving practices.