This higher tier covers Higher Tier: Braking Force and Friction 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 9 of 12 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
🎓 Higher Tier: Braking Force and Friction
When a large braking force is applied to a vehicle, large amounts of heat are generated in the brakes. If brakes overheat (e.g., on steep descents), they become less effective — brake fade reduces the available braking force and greatly increases stopping distance.
The relationship between braking force and deceleration comes from Newton's Second Law: F = ma, so a = F/m. For a 1200 kg car with a 6000 N braking force: a = 6000/1200 = 5 m/s². Using v² = u² + 2as with v = 0: braking distance s = u²/(2a).
Students are expected to be able to estimate the forces involved in typical road scenarios and comment on whether they are safe or dangerous.
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.