Question

the length of a train is 140 m and it's speed is 72km/hr. how long it will take to cross the following​

Answer 1

i)

The speed of train = 72 km/hr = 72 × (5/18) = 20 m/sec.

Time taken by train to cross a pole = length of train/speed of train

Time taken = 140 /20 = sec. = 7 sec.

ii)

now distance = 140 + 220 = 360

time = distance/ speed

time = 360/20 = 18 sec

(here speed is taken 20m/sec. when you will convert 72kmph to m/sec .. its 20.m/sec))

hope its helpful)