Question

A man sitting in a train which is running at 50 Kmph observes that a goods train running in opposite direction takes 9 seconds to pass him. If the goods train is 280 m long, find its speed.
1. 52 Kmph
2. 50 Kmph
3. 56 Kmph
4. 62 Kmph

Answer 1

Correct Answer - Option 4 : 62 Kmph

Concept used:

When to bodies move in opposite direction, then the Relative Speed = Sum of Speeds.

To convert kilometers per hour to meters per second, multiply it with 5/18

Formula used:

Time = Distance/Speed 

Calculation:

Let the speed of the goods train be x km/hr

Relative speed = (50 + x)km/hr = (50 + x) × 5/18 m/s

According to the question:

280/(50 + x) × 5/18 m/s = 9

⇒ 250 + 5x = 280 × 2

⇒ 250 + 5x = 560

⇒ 5x = 560 – 250 = 310 

⇒ x = 310/5 = 62 km/hr

∴ Its speed is 62 kmphr.