Two trains of equal speed are running in opposite directions. If their lengths are 120 metres and 140 metres and they cross each other in 10sec, then find the speed of each train.

Correct option is A

Given:

Two train lengths are 120 metres and 140 metres

Cross each other in 10sec 

Formula Used:​

​$$\text{time} = \frac{\text{Distance}}{\text{Speed}}$$​​

Solution:

Let the speed of each train be ‘x’ m/s

The trains are running in opposite directions, their relative speed is the sum of their individual speeds

Relative speed = 2x m/s

Now,

Time taken to cross = $$\frac{\text{Sum of lengths of train}}{\text{Relative speed}}$$​​

​$$10 = \frac{(120 + 140)}{2x}$$​​

2x = $$\frac{260}{10}$$​​

2x = 26

x = 13 m/s

Speed of each train 13m/s