Two trains are each 50 m long moving parallel towards each other at speeds `10 ms^(-1)` and `15 ms^(-1)` respectively, at what time will they pass each other ?

Options

A. `5 sqrt((2)/(3))`sec
B. 4 sec
C. 2 sec
D. 6sec

Answer

B

Explanation

Relative speed of each train with respect to each other be, `v= 10 + 15 = 25m//s`
Here distance covered by each train = sum of their lengths `=50+ 50 = 100m`
`:.` Required time `=(100)/(25) = 4` sec