# Passenger trains run on parallel tracks towards each other, the length of each train is 150 m.

July 29, 2021 | education

| **Passenger trains run on parallel tracks towards each other, the length of each train is 150 m. The speed of the first is 90 km / h. The passenger on the first train noticed that the oncoming train passed him in 2 seconds. Determine the speed of the oncoming train.**

Data: oncoming traffic; L (length of each train) = 150 m; V1 (speed of the first train) = 90 km / h (in SI V1 = 25 m / s); t (duration of observation by a passenger of an oncoming train) = 2 s.

To determine the required speed of the oncoming train, we use the equality: V1.2 = V1 + V2 = L / t, whence V2 = L / t – V1.

Calculation: V2 = 150/2 – 25 = 75 – 25 = 50 m / s or 180 km / h.

Answer: The sought speed of the oncoming train is 180 km / h (50 m / s).

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