At 60 mph, how much longer is the required stopping distance compared to 20 mph?

The correct answer is based on the physics of stopping distance, which increases with the square of the speed. At higher speeds, not only does the vehicle travel further in the same amount of time, but it also requires more distance to come to a complete stop.

When a vehicle is traveling at 20 mph, the stopping distance is relatively short, as the amount of kinetic energy that needs to be dissipated is manageable. However, when increasing to 60 mph, the kinetic energy triples (since energy is proportional to the square of speed), resulting in a stopping distance that is significantly longer to safely bring the vehicle to a stop.

The mathematical relationship shows that if you compare the stopping distances at 20 mph (which can be represented as 1 unit) versus at 60 mph (which computes to 9 units), the stopping distance at 60 mph is indeed nine times greater than at 20 mph. This dramatic increase illustrates the importance of speed management and awareness of stopping distances in driving safely, particularly at higher speeds.