Question

Two trains are running at $40$ km/hr and $20$ km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in $5$ seconds. What is the length of the fast train?

• A. $23$ m
• B. $23\frac{2}{9}m$
• C. $27$ m
• D. $27\frac{2}{9}m$

Answer 1

The correct option is D $27\frac{2}{9}m$

Relative speed $=(40-20)$ km/hr $=$ $(20\times \frac{5}{18})$ m/s $=\frac{50}{9}$ m/s
$\therefore$ Length of the faster train $=$ $(\frac{50}{9}\times 5)$ m $=\frac{250}{9}$ m $=27\frac{7}{9}$ m