Two trains 85 m and 155 m long, run at the speeds of 62 km/h and 82 km

1.	Two trains 85 m and 155 m long, run at the speeds of 62 km/h and 82 km/h respectively, in opposite directions on parallel tracks. The time which they take to cross each other is:1. 4 seconds2. 5 seconds3. 6 seconds4. 8 seconds
Answer» Correct Answer - Option 3 : 6 seconds Given: Length of two trains is 85 m and 155 m Speed of two trains is 62 km/h and 82 km/h. Formula Used: Speed = Distance/Time Speed adds in opposite direction. To convert km/h into m/s multiply by 5/18 Calculation: Let the two trains be t1 and t2 with length l1 = 85 m and l2 = 155 m and speed s1 = 62 km/h and s2 = 82 km/h. Total length = l1 + l2 ⇒ 85 + 155 ⇒ 240 m Total speed = s1 + s2 ⇒ 62 + 82 ⇒ 144 km/h now, convert speed in m/s ⇒ 144 × 5/18 ⇒ 40 m/s Speed = Distance/Time ⇒ 40 = 240/Time ⇒ Time = 240/40 ⇒ Time = 6s ∴ The time taken by trains to cross each other in 6 seconds.

Two trains 85 m and 155 m long, run at the speeds of 62 km/h and 82 km/h respectively, in opposite directions on parallel tracks. The time which they take to cross each other is:1. 4 seconds2. 5 seconds3. 6 seconds4. 8 seconds

Answer» Correct Answer - Option 3 : 6 seconds

Given:

Length of two trains is 85 m and 155 m

Speed of two trains is 62 km/h and 82 km/h.

Formula Used:

Speed = Distance/Time

Speed adds in opposite direction.

To convert km/h into m/s multiply by 5/18

Calculation:

Let the two trains be t1 and t2

with length l1 = 85 m and l2 = 155 m

and speed s1 = 62 km/h and s2 = 82 km/h.

Total length = l1 + l2

⇒ 85 + 155 ⇒ 240 m

Total speed = s1 + s2

⇒ 62 + 82 ⇒ 144 km/h

now, convert speed in m/s

⇒ 144 × 5/18

⇒ 40 m/s

Speed = Distance/Time

⇒ 40 = 240/Time

⇒ Time = 240/40

⇒ Time = 6s

∴ The time taken by trains to cross each other in 6 seconds.

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