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A truck driver driving at the speed of 54 km h⁻¹ notices a road sign with a speed limit of 40 km h⁻¹ for trucks. He slows down to 36 km h⁻¹ in 36 s. What was the distance travelled by him during this time? Assume the acceleration to be constant while slowing down.
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\(u = 54\ \text{km h}^{-1} = 15\ \text{m s}^{-1},\ v = 36\ \text{km h}^{-1} = 10\ \text{m s}^{-1},\ t = 36\ \text{s}\).
Distance = average velocity × time \(= \dfrac{15 + 10}{2} \times 36 = 12.5 \times 36 = 450\ \text{m}\).
