A passenger of a train traveling at a speed of 15 m / s sees in the window an oncoming train 150 m

A passenger of a train traveling at a speed of 15 m / s sees in the window an oncoming train 150 m long for 6 s. At what speed is the oncoming train.

Since the trains are moving towards each other, the total speed of their movement is equal to:
V = V1 + V2, where V1 is the speed of the first train (V1 = 15 m / s), V2 is the speed of the second (oncoming) train (m / s).
The total train speed can be calculated using the formula:
V = S / t, where S is the distance traveled, the length of the oncoming train (S = 150 m), t is the travel time (t = 6 s).
V = S / t = 150/6 = 25 m / s.
V2 = V – V1 = 25 – 15 = 10 m / s.
Answer: The oncoming train is moving at a speed of 10 m / s.