# The lengths of the trains going in opposite directions having speeds of 100 km/h and 104 km/h are 250 m and 260 m. After how many seconds they will cr

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The lengths of the trains going in opposite directions having speeds of 100 km/h and 104 km/h are 250 m and 260 m. After how many seconds they will cross each other ?
1. 15 second
2. 5 second
3. 12 second
4. 16 second
5. 9 second

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Correct Answer - Option 5 : 9 second

Given:

Speed of the first train (S1) = 100 km/h

Speed of another train (S2) = 104 km/h

Length of the first train (L1) = 250 m

Length of another train (L2) = 260 m

Concept Used:

When trains running in opposite direction crosses each other then, Relative Speed = S+ S2

Distance = Speed × Time

Calculation:

According to the question,

Relative Speed = (100 + 104) km/h

⇒ 204 km/h

For 'm/s', Relative Speed = 204 × (5/18) m/s

Now, Time = (L+ L2)/Relative Speed

⇒ (250 + 260)/[204 × (5/18)]

⇒ (510 × 9)/(102 × 5)

⇒ 9 sec.

∴ Both train will cross each other in 9 seconds.