The relative speed in the same direction = Difference of speed Calculation: The relative speed of both train as they are moving in the same direction ⇒(90 – 80)
km
hr
=10
km
hr
Relative speed in
m
s
⇒10×
5
18
=
25
9
m
s
Now distance covered by the faster train is equal to its length (X). Time taken = 54 secs Distance = speed × time ⇒X=
25
9
×54=150m ∴ The length of the faster train is 150 m.