This exam tips covers Exam Tips for Stopping Distances within Stopping Distances for GCSE Physics. Revise Stopping Distances in Forces for GCSE Physics with 15 exam-style questions and 5 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 11 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
💡 Exam Tips for Stopping Distances
🎯 Common Question Types:
- Calculate thinking distance (speed × reaction time) — 1-2 marks
- State TWO factors affecting braking distance — 2 marks
- Explain why speeding is dangerous using physics (braking ∝ v²) — 3 marks
- Describe the effect of alcohol on stopping distance — 2-3 marks
📝 Key Command Words:
- State: Just name the factor — no explanation needed
- Explain: State the factor → link to reaction time or friction → link to distance
- Calculate: Show thinking distance = speed × reaction time
- Describe: Mention all three stages (see hazard → react → brake → stop)
⚠️ Common Mistakes to Avoid:
- Saying "stopping distance doubles when speed doubles" — it more than doubles
- Mixing up which factors affect thinking vs braking distance
- Forgetting that wet roads affect braking distance, NOT thinking distance
- Not linking braking distance to kinetic energy in "explain" questions
Quick Check: A car doubles its speed from 10 m/s to 20 m/s. What happens to: (a) thinking distance and (b) braking distance?
(a) Thinking distance doubles (proportional to v). (b) Braking distance quadruples (proportional to v²). This is because kinetic energy = ½mv², so four times the energy must be transferred by the brakes.
Quick Check: Give TWO factors that affect braking distance but NOT thinking distance.
Any two from: condition of tyres (worn tyres = less grip), road surface (wet/icy roads = less friction), condition of brakes (worn brakes = less braking force), mass of vehicle (heavier = more KE to transfer). Remember: thinking distance is about the DRIVER, braking distance is about the CAR and ROAD.
Practice questions for Stopping Distances
What is the correct definition of stopping distance?
Explain why a car travelling at higher speed has a greater braking distance than a car travelling at lower speed, assuming the same braking force.