New Hampshire Drivers Practice Test

When you double your speed, the stopping distance increases by a factor of four due to the physics of kinetic energy and braking distance. Stopping distance consists of thinking distance and braking distance. The thinking distance, which is the distance covered while a driver reacts to a hazard, may not significantly change with speed. However, the braking distance, which is affected by the vehicle's speed, is a crucial factor. This braking distance is mathematically related to the speed of the vehicle: if the speed doubles, the braking distance quadruples because it is proportional to the square of the velocity. In practical terms, at higher speeds, a vehicle has more kinetic energy, and it takes a greater distance to come to a complete stop. For example, if a vehicle traveling at 50 mph takes a certain distance to stop, a vehicle traveling at 100 mph would not just take double that distance; it would take four times as long to stop safely. Hence, the correct answer reflects the significant increase in stopping distances associated with higher speeds.