Question

Two trains each of length 100 m moving parallel
towards each other at speed 72 km/h and
36 km/h respectively. In how much time will they
cross each other?​

Answer 1

Answer:

20/3 s

Explanation:

easy way to solve using relative velocity i.e.,

Let's assume the first train at rest

the other train appears to cross the first train at 36+72 = 108kmph

the moving train has to cross the trains length as well as its length to say that the trains crossed each other

so the problem now becomes

how much time is taken by the moving train @108kmph to cross 200m

first convert kmph to m/s by multiplying 5/18

108kmph = 108 x (5/18) = 30m/s

time taken = distance/speed = 200/30 = 20/3 s