Discussion of Question with ID = 090 under Problems-on-Trains

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Question

Two trains moving in the same direction, and running respectively at 72km/h and 144km/h cross each other in 5sec. What is the length of each train if the two trains are equally long?

A

50 m.

B

51 m.

C

49 m.

D

52 m.

Soln.
Ans: a

The trains cover a distance equal to the sum of their lengths at a relative speed 144 - 72 = 72km/h × (5/18), or 20m/s. We can use the speed distance formula: sum of lengths = 20 × 5 = 100m. Halving this we get the length of one train = 50m.


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