Free taster
5 of 6 sections open
The Hidden Danger of Speed
📖 The Hidden Danger of Speed
At 30 mph, a car needs about 23 metres to stop. At 60 mph — just double the speed — it needs about 73 metres! That's more than THREE times the distance. Why? Because thinking distance doubles (you travel twice as far during reaction time), AND braking distance QUADRUPLES (kinetic energy is proportional to v²). This is why speed limits exist near schools — the physics of stopping makes high speeds deadly.
Factors Affecting THINKING Distance
Thinking distance = speed × reaction time
Earn the mark scheme marks
🧠 Memory Aid
Thinking vs Braking — "Driver vs Car":
Thinking distance is all about the DRIVER — their reaction time, whether they're tired, drunk, or distracted.
Braking distance is all about the CAR and ROAD — tyre grip, brake quality, road surface, vehicle mass.
Speed and distance relationship:
- Thinking distance ∝ v (speed doubles → thinking distance doubles) — linear relationship
- Braking distance ∝ v² (speed doubles → braking distance ×4) — squared relationship
Memory trick: "Thinking is T (linear), Braking is B (bigger — squared)"
Now try it yourself
Quiz · Question 1 of 15
What is the correct definition of stopping distance?
Tap an answer to check it
This topic in real past papers
Every real exam question we've found on stopping distances, with a full worked answer.