When you double your speed from 20 to 40 mph, the impact in a crash is:
Correct. Crash energy is proportional to the square of speed. Doubling speed quadruples the energy of impact.
CDL Practice Question #31
Category: General Knowledge
Why this question matters
This question is one of 97 in our General Knowledge bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.