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# A car moving along a straight highway with speed $126\;km/hr$ is brought to a stop with in a distance of 200 m . ?What is the retardation of the car, and how long does it take for the car to stop .

$\begin{array}{1 1} (a) \;11.44\;s \\ (b) \;20.61\;s \\ (c) \;14.2\;s \\ (d) \;15.0\;s\end{array}$

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A)
Solution :
Initial velocity = 126 km/hr
Final velocity=0
Distance = 200 m
Using $S= \large\frac{v^2-u^2}{2a}$
$200 =\large\frac{0-35^2}{2a}$
=> $a= -3.06$
Using $v=u+at$
$O= 35-(3.06)t$
$t= \large\frac{35}{3.06}$$=11.44\;s$