Question

Find the time taken by a train of length 225 m, travelling at a speed of 45 km/h, to
cross
i) a man standing on a railway platform
ii) a platform of length 475 m.
​

Answer 1

Given that:

• Length of train=225cm
• Speed =45km/h
• Length of platform=475m

To find:

1. What is the time taken by a train to cross a man standing on the platform.
2. Time taken to cross a platform of length 475 m.

Solution :

i. To find the time taken by the train to cross a stationary man.

Speed of train in m/s

$\leadsto\dfrac{45×1000}{60×60}$

$\leadsto\dfrac{25}{2}m/s$

Distance covered=Length of train=225 m

Time taken$\leadsto\dfrac{Distance}{Speed}$

$\leadsto225÷\dfrac{25}{2}$

$\leadsto\dfrac{225×2}{25}$

$\leadsto\rm{9×2=18 s}$

ii)Time taken to cross the platform.

Distance covered=Length of train+Length of platform

$\leadsto{225m+475m=700m}$

Speed of train$\leadsto\dfrac{25}{2}m/s$

Time taken$\leadsto700÷\dfrac{25}{2}=56 s.$

$\sf\blue{Final\:ans:-}$

i)$\mapsto{18 s}$

ii)$\mapsto{56 s}$