Question

A 360m long train crosses a pole in 12 seconds. How long it take to pass a platform 900m long?​

Answer 1

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Length of train= Distance covered by train

$\sf \: Speed = \frac{distance}{time}$

$\sf \: Speed \: of \: train = \frac{360}{12} = 30m/s$

Time taken to cross 900m lobg platform

$\sf \: Time = \frac{distance}{time}$

$= \frac{900}{30} = 30$

So time taken is 30 seconds.

Hope it helps you.....

Answer 2

Given: A 360m long train crosses a pole in 12 seconds.

To find: Time taken to cross a 900 m long platform

Solution: Length of the train= 360 m

Time taken in crossing the pole = 12 s

Since a pole has no length horizontally, the total distance covered by train is equal to the length of the train.

Speed of train

= Distance covered/ Time taken

= 360 m / 12 s

= 30 m/s

When it passes the 900 m platform, the total distance covered by train is equal to the sum of the length of the platform and length of the train because here, the train has to cross the platform completely.

Total distance= 900 m + 360 m

= 1260 m

Time taken

= Distance covered/ Speed

= 1260 m / 30 m/s

= 42 seconds

Therefore, the time taken to cross the platform is 42 seconds.