FRICTION AND BRAKING
3 marks · EasyDescribe how the following factors each affect a car's braking distance.
| Factor |
|---|
| Speed of the car |
| Condition of the tyres |
| Mass of the vehicle |
Give a brief explanation for each factor.
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Greater speed increases braking distance as more energy must be removed. Poor tyre condition (e.g., worn, under-inflated) increases braking distance due to less friction. Higher mass increases braking distance because heavier vehicles require more force to stop in the same distance.
Must show: For speed: state and explanation, For tyre condition: state and explanation, For mass: state and explanation
Also accept: Any scientifically valid explanation using the ideas of energy, force, and friction as described in the content.
Common mistakes: Only listing factor without explanation; Mixing up effects on thinking distance or braking distance
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Describes how higher speed increases braking distance and gives a correct scientific reason (e.g., more energy to remove).
B2 · 1 mark · Describes how poor tyre condition increases braking distance because of reduced friction.
B3 · 1 mark · Describes how greater mass increases braking distance and gives a correct reason (more force needed for same deceleration).
Worked solution
Speed of the car: A higher speed increases the braking distance because the car has more kinetic energy, so needs to travel further while brakes remove the energy.
Condition of the tyres: Poor or worn tyres reduce the friction between the tyres and road, so braking distance increases as less force is available to stop the car.
Mass of the vehicle: A greater mass means the car requires more force to stop in the same distance. For the same braking force, a heavier vehicle will have a longer braking distance.