A car travels at 25 m/s. A stationary obstacle is 70 m ahead when it is first detected. The braking distance is 50 m. A human driver has a reaction time of 1.0 s; an automatic system has a delay of 0.20 s. Which statement is correct?
The human-controlled car stops 5 m before it; the automatic car reaches the obstacle.
The human-controlled car reaches the obstacle; the automatic car stops 15 m before it.
The human-controlled car reaches the obstacle; the automatic car stops 20 m before it.
The human-controlled car stops 5 m before it; the automatic car stops 15 m before it.
126 exam-style questions on Edexcel GCSE Physics 2.5 Stopping and braking distances, covering 2.5.1 Stopping distance and reaction time, 2.5.2 Factors affecting stopping distance, 2.5.3 Dangers of large decelerations, and 2.5.4 Braking distance and initial speed. Each one has a worked solution and a mark scheme showing where the marks go.