A car travelling at 72 km/h brakes with a constant deceleration of 4 m/s^2. What is the braking distance?
Answer and explanation
Correct answer: A. 50 m
- Step 1: The speed is 20 m/s.
- Step 2: Braking distance = v^2 / (2a) = 400 / 8 = 50 m.
Answer
50 m.
Why not the others: The factor 2 in the denominator matters; leaving it out doubles the distance, and dividing the speed by 2a instead of squaring it gives far too little.
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