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Zorluk: ZorAdjusting Margins in Wet Weather

On a dry asphalt road, a motor car travelling at 40 mph requires an average thinking distance of 12 metres (40 feet) and a braking distance of 24 metres (80 feet). When driving on the same road surface during a heavy downpour, what is the vehicle's total stopping distance?

  1. A
    48 metres
  2. 60 metresCevap
  3. C
    72 metres
  4. D
    252 metres

Cevap

60 metres (12 metres thinking distance + 48 metres braking distance)
In wet conditions, surface water reduces friction between tyres and the road, causing the vehicle's braking distance to double from 24 metres to 48 metres. Because the driver's reaction speed is unchanged, thinking distance remains 12 metres. Combining these gives a minimum total stopping distance of 12 m+48 m=60 metres12\text{ m} + 48\text{ m} = 60\text{ metres}.

Adım Adım Çözüm

1
Identify the base stopping distance components at 40 mph under dry conditions.
Thinking distance is 12 metres and braking distance is 24 metres.
Overall stopping distance is calculated by adding thinking distance to braking distance.
2
Apply the wet weather factor to each individual component.
Thinking distance remains 12 metres; braking distance doubles from 24 metres to 48 metres (24 m×2=48 m24\text{ m} \times 2 = 48\text{ m}).
Water on the road reduces tyre adhesion, which doubles the distance required to bring the vehicle to a halt, but does not alter driver perception or reaction time.
3
Calculate the adjusted total stopping distance.
Total stopping distance is 12 m+48 m=60 metres12\text{ m} + 48\text{ m} = 60\text{ metres}.
Summing the unchanged thinking distance and the doubled braking distance provides the safe stopping margin.

Anahtar Kavram

Calculating stopping distance in wet weather by doubling braking distance while keeping thinking distance constant
Tahmini Süre:1m 0s
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Konular

Adjusting Margins in Wet Weather

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