The blue car in the picture is following the red car. What is the minimum gap its driver should leave?
Correct answer: One car length for each 10 mph, or 3 seconds of travel.
Answer options
AOne car length at any speed, or half a second of travel
BOne car length for each 30 mph, or 1 second of travel
COne car length for each 10 mph, or 3 seconds of travel Correct
Why
The usual guideline is one car length for every 10 mph, or a gap of at least 3 seconds: when the red car passes a fixed point such as a pole, the blue car should not get there until three seconds have gone by. A gap of a second or less leaves no time to react if the red car brakes hard.