Question

Difficulty: EasyFactors Affecting Braking Distance

On a dry road surface, a car travelling at 40 mph has an average braking distance of 24 metres. According to the Highway Code, wet road conditions reduce tyre grip such that braking distance is at least double that on a dry road. What is the estimated braking distance, in metres, when stopping on a wet road from the same speed?

Answer: 48 metres

Answer

48 metres

According to the Highway Code, surface water reduces tyre adhesion, causing the braking distance on wet roads to be at least double that on dry roads. Multiplying the dry braking distance of 24 metres by 2 results in 48 metres.

Step-by-Step Solution

1

Identify the dry road braking distance and the relevant environmental multiplier.

Baseline dry braking distance = 24 metres; wet road multiplier = 2

The Highway Code establishes that wet conditions reduce surface friction, doubling the distance required to bring the vehicle to a stop once brakes are applied.

2

Multiply the baseline braking distance by the wet road multiplier.

24 \times 2 = 48 \text{ metres}

Multiplying the dry distance by 2 gives the minimum expected braking distance on a wet surface.

Key Concept

Braking distance is at least doubled on wet roads compared to dry roads due to reduced tyre-to-road friction.

Estimated Time:30s

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Factors Affecting Braking Distance

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