Two trains travel towards the opposite direction at speeds of 15 and 21 m / s, the first train notices

| July 7, 2021 | education

Two trains travel towards the opposite direction at speeds of 15 and 21 m / s, the first train notices the second one passes it in 5 seconds what is the length of the second train.

V1 = 15 m / s.

V2 = 21 m / s.

t = 5 s.

L2 -?

The travel time of the second train relative to the first t is expressed by the formula: t = L2 / V21, where L2 is the length of the second train, V21 is the speed of the second train relative to the first.

L2 = V21 * t.

Since the trains are moving towards each other, the speed of the second train relative to the first 21 will be the sum of the train speeds relative to the earth’s surface: V21 = V1 + V2.

The length of the second train will be determined by the formula: L2 = (V1 + V2) * t.

L2 = 15 m / s + 21 m / s) * 5 s = 180 m.

Answer: the second train has a second length L2 = 180 m.



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