By how much does stopping distance increase when you double your speed?

Prepare for the Alabama CDL Class A Permit Test. Study with flashcards and multiple-choice questions, each question includes hints and explanations. Ace your exam!

Multiple Choice

By how much does stopping distance increase when you double your speed?

Explanation:
Stopping distance grows much faster than your speed because it has two parts: reaction distance and braking distance. Reaction distance increases in direct proportion to speed, while braking distance increases with the square of speed. So when you double your speed, the reaction part becomes twice as long, and the braking part becomes four times as long. Since braking distance is typically the larger portion of the total stopping distance at normal driving speeds, the overall stopping distance ends up about four times longer. That’s why the correct answer is four times the original stopping distance.

Stopping distance grows much faster than your speed because it has two parts: reaction distance and braking distance. Reaction distance increases in direct proportion to speed, while braking distance increases with the square of speed. So when you double your speed, the reaction part becomes twice as long, and the braking part becomes four times as long. Since braking distance is typically the larger portion of the total stopping distance at normal driving speeds, the overall stopping distance ends up about four times longer. That’s why the correct answer is four times the original stopping distance.

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