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South Carolina Class D Knowledge Test Practice
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Observation, Speed & SpaceStandalone practice
At 50 mph on dry pavement with good brakes, braking alone can take about 158 feet. Why is your total stopping distance longer than that?
Correct answer: You also travel while you recognize the hazard and while you move your foot to the brake.
Why
At 50 mph a vehicle covers about 73 feet each second, so 1.5 to 2 seconds of perception and reaction time adds about 110 to 150 feet before the brakes begin to work. Speed makes every part longer, and braking distance grows fastest as speed goes up. A tired, distracted or impaired driver takes longer to perceive and react, which adds still more distance.
Verified against South Carolina Driver's Manual · Stopping distance · p. 98
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