North Dakota Class D Knowledge Practice Test
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Passing target: 80% (24/30)
You usually drive a street at 30 mph. Today you drive a highway at 60 mph, twice as fast. Compared with 30 mph, about how long is your braking distance at 60 mph?
Two views show the same blue car on a straight road, first at 30 mph and then at 60 mph. Neither view selects a braking distance.
Correct answer: About four times the distance
Why
Your total stopping distance also includes the road that you cover before your foot reaches the brake, and at a higher speed you cover more of it. Weight adds to the effect: double the weight and the braking distance doubles, so a trailer or a heavy load at high speed needs much more room. This is why crash risk and crash force both rise as speed rises.
Verified against 2025-2027 Class D Noncommercial Driver License Manual · Tips for supervising teen driving · p. 46, 27, 45
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