Question

A train 270m long is running at 80 km/hr.How much time will it take to cross a platform 130m long?

Answer 1

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Given,
Length of the train = 270 m
Speed of the train =80 kmph
Length of platform = 130 m

----- Convert Speed of train in kmph to mps
We have,
$1\: kmph = \frac{5}{18}\: mps$

$80\: kmph = 80 × \frac{5}{18} = 40 × \frac{5}{9}$

$\implies 80\: kmph = \frac{200}{9}\: mps$

----- Find Distance covered by train

Distance covered by train in passing the platform equals Sum of the lengths of the train and the platform.
$\implies Distance \: covered = 270+130=400\: m$

---- We have,
$Speed = \frac{Distance\: Covered}{Time\: taken}$

Therefore,
$time\: taken = \frac{Distance\: Covered}{Speed}$

$\implies time\: taken = \dfrac{400}{\frac{200}{9}}$

$\implies time\: taken = 2 \times 9 = 18\: sec$

Therefore,
time taken by train to cross the platform is 9 sec