New Hampshire Non-Commercial Operator Knowledge Practice Test
Full test preview Question 1 of 40
0 answered 40 remaining
Passing target: 80% (32/40)
On a 30 mph road, you stayed about 180 feet behind the car ahead, which was about a four-second gap. Now you drive at 60 mph on a highway, still about 180 feet behind the car ahead. What should you do?
Two views show A following B with the same 180-foot bumper-to-bumper gap: first at 30 mph, then at 60 mph. Only the earlier 30 mph view is identified as about four seconds.
Correct answer: Drop back until you count at least four seconds, which is about 350 feet at 60 mph
Why
The manual says that stopping distance becomes about 4 times as long when speed doubles, because you cover more ground while you react and the brakes need much more distance. A time gap grows in feet as your speed goes up, which is why the four-second count works on every road. Count the seconds from a fixed point often on the highway, and add time in rain, snow, fog or darkness.
Verified against New Hampshire Driver's Manual · High-speed following · p. 22, 36
Report a question issueContinue learning