You are driving at 80 km/h on the road between Nijverdal and Wierden. You see that the car ahead has to brake hard. How long is your stopping distance, from the moment you see it until you stand still?
- ✓ About 54 metres
- About 32 metres
- About 86 metres
Correct answer: About 54 metres
Explanation
False — you calculate the braking distance without dividing by 2. Braking distance = (speed : 10) x (speed : 10) : 2, so at 80 km/h (8 x 8) : 2 = 32 m, not 64 m. Adding about 22 m of reaction distance, the stopping distance is 54 m
Why learners get this wrong
- Wrong: you count only the braking distance and forget the distance you cover before you brake. Stopping distance = reaction distance + braking distance. At 80 km/h: about 22 m reaction distance + 32 m braking distance = 54 m
- Wrong: you calculate the braking distance without dividing by 2. Braking distance = (speed : 10) x (speed : 10) : 2, so at 80 km/h (8 x 8) : 2 = 32 m, not 64 m. Adding about 22 m of reaction distance, the stopping distance is 54 m
Topic: The braking-distance rule of thumb: (speed:10)² : 2
Read the rule: Core: The braking-distance rule of thumb: (speed:10)² : 2
Sections
- Challenge: The braking-distance rule of thumb: (speed:10)² : 2
- The model: The braking-distance rule of thumb: (speed:10)² : 2
- Core: The braking-distance rule of thumb: (speed:10)² : 2
- Why it matters: The braking-distance rule of thumb: (speed:10)² : 2
- Active recall: The braking-distance rule of thumb: (speed:10)² : 2
- Teach back: The braking-distance rule of thumb: (speed:10)² : 2
- Memory hook: The braking-distance rule of thumb: (speed:10)² : 2