Two trains of equal length are running on parallel lines in the same direction at $46$ km/hr and $36$ km/hr. The faster train passes the slower train in $36$ seconds. The length of each train is

The correct option is A $50$ m
Let the length of each train be $x$ m.
During crossing, the two trains cover a distance equal to sum of their lengths.
Then, distance covered $=2x$ m.
Relative speed $=46-36=10$ km/hr
$=10\times \frac{5}{18}=\frac{25}{9}$ m/sec
$\text{Speed}=\frac{\text{Distance}}{\text{Time}}$
$\Rightarrow \frac{25}{9}=\frac{2x}{36}$
$\Rightarrow x=50$
Hence, the length of each train is $50$ m.