Question
Download Solution PDFTwo trains are running on opposite tracks between stations A and B. After crossing each other they take 4 hr and 9 hr respectively to reach their destination. If speed of first train is 54 kmph, find the speed of second train.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
Two trains are running on opposite tracks between stations A and B.
After crossing each other they take 4 hr and 9 hr respectively to reach their destination.
Speed of first train is 54 kmph.
Formula used:
After crossing each other, if time taken by 2 trains is T1 and T2 resp. then, S1/S2 = √T2/√T1
where, S1 and S2 are speeds of first and second train respectively
Calculation:
We have, T1 = 4hr, T2 = 9hr, S1 = 54 kmph
⇒ 54/ S2 = √[9/4] = 3/2
⇒ S2 = 54 × 2 × 1/3 = 36 kmph
⇒ Speed of second train = 36 kmph
Alternate Method
Let the speed of the second train be 'x' kmph
Also, time taken to cross each other = √(T1 × T2) = √(9 × 4) = 6 hrs
Total distance = 54 × 6 + x × 6 = x × 9 + 54 × 4
⇒ 9x - 3x = 54 × (6 - 2)
⇒ 6x = 216
⇒ x = 36 kmph = Speed of second train
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