Braking distance refers to the amount of space it takes for a vehicle to come to a complete stop. This distance varies greatly between different types of vehicles. A train, for instance, takes almost a mile to stop. The length, weight, and speed of a train make it difficult to stop. The general rule of thumb for a standard sedan is one car length. Again, the weight and speed of vehicle will play a major role in its ability to stop quickly. The heavier and faster a vehicle is moving relates to the amount of inertia that vehicle has. The greater the inertia the harder the brakes must work to halt the vehicle.
HELLO! This means the distance required for a vehicle moving at a specified velocity to come to a complete stop after its breaks have been activated.