Question

Two trains having lengths of 150m and 350m are running at speeds of 60km/h and 120km/h respectively, in the same direction. The time taken (in minutes) by the faster train, coming from behind, to completely cross the other train is :

• A. 2
• B. 1.2
• C. 3.5
• D. 0.5

Answer 1

Answer:

D. 0.5

When trains move in the same direction, use relative speed = difference of speeds.

Total distance to be covered

To completely cross:
$150 + 350 = 500 \text{ m}$

Relative speed

$120 - 60 = 60 \text{ km/h}$

Convert to m/s:
$60 \times \frac{5}{18} = 16.67 \text{ m/s}$

Time

$\text{Time} = \frac{500}{16.67} \approx 30 \text{ seconds}$

Convert to minutes

$30 \text{ sec} = 0.5 \text{ minutes}$

Final Answer: 0.5 minutes