A train, 150 m long, passes a pole in 15 seconds and another train of

1.	A train, 150 m long, passes a pole in 15 seconds and another train of the same length travelling in the opposite direction in 10 seconds. The speed of the second train is1. 18 m/s2. 20 km/h3. 10 m/s4. 20 m/s
Answer» Correct Answer - Option 4 : 20 m/s Given: Length of train = 150 m Time taken by train to pass a pole = 15 seconds Time taken by train to pass the same length of train which are running in the opposite direction = 10 seconds Formula used: Distance = speed × time Concept used: If the speed of A is x km/h and that of B is y km/h. then Relative speed of A and B moving in opposite direction = (x + y) km/h. Calculations: Let the speed of the second train be x m/s Speed of the first train = 150/15 = 10 m/s Relative speed of trains = (x + 10) m/s Total distance covered = 150 + 150 = 300 metres so time taken = 300/(x + 10) According to the question ⇒ 10 = 300/(x + 10) ⇒ 10x + 100 = 300 ⇒ 10x = 200 ⇒ x = 20 ∴ The speed of second train is 20 m/s

A train, 150 m long, passes a pole in 15 seconds and another train of the same length travelling in the opposite direction in 10 seconds. The speed of the second train is1. 18 m/s2. 20 km/h3. 10 m/s4. 20 m/s

Answer» Correct Answer - Option 4 : 20 m/s

Given:

Length of train = 150 m

Time taken by train to pass a pole = 15 seconds

Time taken by train to pass the same length of train which are running in the opposite direction = 10 seconds

Formula used:

Distance = speed × time

Concept used:

If the speed of A is x km/h and that of B is y km/h.

then Relative speed of A and B moving in opposite direction = (x + y) km/h.

Calculations:

Let the speed of the second train be x m/s

Speed of the first train = 150/15 = 10 m/s

Relative speed of trains = (x + 10) m/s

Total distance covered = 150 + 150 = 300 metres

so time taken = 300/(x + 10)

According to the question

⇒ 10 = 300/(x + 10)

⇒ 10x + 100 = 300

⇒ 10x = 200

⇒ x = 20

∴ The speed of second train is 20 m/s