On a wet road the braking distance is roughly twice as long as on a dry road. With the Swiss rules of thumb, what is the stopping distance at 40 km/h on a wet road (reaction distance = speed ÷ 10 × 3, dry braking distance = (speed ÷ 10)²)?
Answer and explanation
Correct answer: A. 44 m
- Step 1: Reaction distance = 12 m; wet braking distance = 2 × 16 = 32 m. Step 2. Stopping distance = 44 m. Answer: 44 m. Why not the others: 28 m results from having used the dry braking distance. 56 m results from having doubled the whole stopping distance. 40 m results from having doubled the reaction distance instead of the braking distance.
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