Braking distance depends on:
- Speed â braking distance is proportional to v² (double speed = 4à distance)
- Braking force â stronger brakes = shorter distance
- Mass â heavier vehicle = longer to stop
Adverse conditions:
- Wet roads â less friction, longer braking
- Icy roads â much less friction, MUCH longer braking
- Worn tyres â less grip
- Worn brakes â less braking force
- Overloaded vehicle â more mass to stop
Why braking distance is proportional to v²: The brakes must transfer ALL the kinetic energy. Since KE = œmv², double speed means 4à energy to transfer!
Quick Check: A driver's reaction time is 0.7 s. The car travels at 20 m/s. Calculate the thinking distance.
Thinking distance = speed à reaction time = 20 à 0.7 = 14 m. This is the distance the car travels before the brakes are even applied.
This key facts covers Factors Affecting BRAKING Distance 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 4 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
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.