Question

Two trains are each $50\text{m}$ long moving parallel towards each other at speeds $10\text{m/s}$ and $15\text{m/s}$ respectively. After what time will they pass each other?

• A. $5\sqrt{\frac{2}{3}}\text{sec}$
• B. $4\text{sec}$
• C. $2\text{sec}$
• D. $6\text{sec}$

Answer 1

The correct option is B $4\text{sec}$

As both the trains are moving in the opposite direction, the relative speed of each train with respect to each other be, $v=10+15=25\text{m/s}$
Here, distance covered by each train = sum of their lengths $=50+50=100\text{m}$
$\therefore$ Required time $=\frac{100}{25}=4\text{sec}$