On dry level pavement at 55 mph, approximately how much distance does a passenger car need to stop completely?

Why B is correct

Total stopping distance has two parts, and only one of them is braking. Perception and reaction consume roughly 60 to 90 feet before the brake pedal is touched at all: at 55 mph a car covers about 80 feet per second, so a single second of delay is already a car and a half of travel. The braking itself, on dry pavement, then needs roughly another 200 feet or more. Added together, a realistic figure is about 300 feet, which is the length of a football field. That is precisely why following distance is taught in seconds rather than in car lengths — time scales with speed, while a fixed count of car lengths does not.

Why the other options are wrong

A. About 200 feet

About 200 feet covers the braking phase but ignores the distance covered while you perceive the hazard and move your foot to the pedal. On a knowledge test, omitting half of the total stopping distance is the wrong half to omit.

C. About 100 feet

About 100 feet is roughly the braking distance at much lower speeds, or the perception distance at 55 mph. It leaves reaction time out entirely, and it would put you into the vehicle ahead long before you came to a stop.

D. About 600 feet

About 600 feet overstates the figure for dry pavement at 55 mph by roughly double. That magnitude belongs to higher speeds, to wet or icy surfaces, or to heavy vehicles — not to a passenger car in good conditions.

On the road

You are on a highway feeder road at 55 mph and the car ahead brakes hard for a stalled vehicle. You see the brake lights, react, and brake. From the moment you noticed to the moment you stopped, you travelled about the length of a football field — which is why a two or three second following gap is a minimum, not a suggestion.

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