Question

please answer this question very urgent don't answer this simply this is an question of direct and inverse proportion....

Answer 1

it will take 20 seconds to cross a telegraph post

Answer 2

So, In this question the length of the train is 400 mtr and the speed of the train is 72 km/hr.

First convert the speed in meters per hour by multiplying it by 5/18.

So the speed of the train is 20 mts/sec.

We know that speed = distance/time.

therefore time=400/20.

Time took to cross the post would be 20 seconds.