Question

Two train are $2$ km apart and their lengths are $200$ m and $300$ m. They are approaching towards each other with a speed of $20$ m/s and $30$ m/s respectively. After how much time will they cross each other?

• A. $50$ seconds
• B. $100$ seconds
• C. $\frac{25}{3}$ seconds
• D. $150$ seconds

Answer 1

The correct option is A $50$ seconds

Relative speed of the trains $=(20+30)$ m/s$=50$ m/s.

Total distance covered $=(2\times 1000+200+300)$ m $=2500$ m.
$\therefore$ The two trains will cross each other after $\frac{2500}{50}$ seconds $=50$ seconds.