Whenever you double your speed, approximately how many times longer is the stopping distance?

Whenever you double your speed, approximately how many times longer is the stopping distance?

• A. 2 times
• B. 3 times
• C. 4 times
• D. 5 times

Answer: (C)

When you stop, the braking distance grows with the amount of energy you have to dissipate, and that energy is proportional to the square of your speed. So if you double your speed, you’re dealing with about four times as much energy to remove. With roughly the same braking capability, it takes about four times as long a distance to shed that energy, making the stopping distance about four times longer. The distance you cover during the driver's reaction also increases with speed, but at typical speeds the braking part dominates the total stopping distance, which is why this rule of thumb is four times longer.

When you stop, the braking distance grows with the amount of energy you have to dissipate, and that energy is proportional to the square of your speed. So if you double your speed, you’re dealing with about four times as much energy to remove. With roughly the same braking capability, it takes about four times as long a distance to shed that energy, making the stopping distance about four times longer. The distance you cover during the driver's reaction also increases with speed, but at typical speeds the braking part dominates the total stopping distance, which is why this rule of thumb is four times longer.