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# Telegraphic poles along a straight railway track are spaced at regular intervals of $90\;m$. A passenger in the train observes the successive pole pass at time intervals of 3 and 2 seconds respectively , find the acceleration of the train assuming it to be uniform .

$\begin{array}{1 1} (A)\;6ms^{-2} \\(B)\;8\;ms^{-2} \\(C)\;7\;ms^{-2} \\(D)\;9\;ms^{-2} \end{array}$

Let the velocity of the train as it crosses certain pole be u.
Since from this pole the distance of the next pole is $90 m$ and next pole is $180m$ , therefore using
$s= ut +\large\frac{1}{2}$$at^2 90=u(3)+\large\frac{1}{2}$$a(3)^2$
$180=u(3+2)+\frac{1}{2}a(3+2)^2$
Solving we get , $a=6 ms^{-2}$
Hence A is the correct answer.