Question

A driver takes 0.20 s to apply the break after he see need for it if he is driving a car at the speed of 54km / hr and the break cause deceleration of6m/s^2 find the distance travelled by a car after he see need for it.

Answer 1

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Answer 2

Hope u like my process
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Before applying brake,
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Time (T) = 0.2 s

Speed (V) = 54km/hr = 15 m/s

So distance travelled (s1) = V×t = 15×0.2 =3m
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Now,
After applying brake
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Initial velocity (u) = 15 m/s

Final velocity (v) = 0 m/s

Deceleration (d ) = 6 m/s²

So distance travelled (s2)

$= \frac{ {u}^{2} - {v}^{2} }{2 \times d} \\ \\ = \frac{ {15}^{2} - 0}{2 \times 6} = 18.75 \: \: m$
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So total distance travelled = s1 +s2

= 3 + 18.75 = 21.75 m ≈22 approx
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