A car travelling at 20 m/s brakes with a constant deceleration and stops in 4 s. How far does it travel while braking?
Answer and explanation
Correct answer: B. 40 m
- Step 1: The average speed during uniform braking is (20 + 0) / 2 = 10 m/s.
- Step 2: Distance = average speed x time = 10 x 4 = 40 m.
Answer
40 m.
Why not the others: 80 m uses the starting speed for the whole time, 5 m is the deceleration in m/s squared and 20 m is half the true distance.
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