Two trains go towards each other at a speed of 45 km / h. The length of each train is 250 m.

Two trains go towards each other at a speed of 45 km / h. The length of each train is 250 m. How many seconds will elapse from the moment the drivers meet until the moment the conductors meet at the last doors of the last cars?

1) If two trains go towards each other each at a speed of 45 kilometers per hour, then their total speed is 90 kilometers per hour;
2) 250 + 250 = 500 meters – their total length, it is the distance between the last doors of the last cars at the time of the meeting of the drivers;
3) 90 km per hour = 90,000 / 3600 = 25 meters per second;
4) 500/25 = 20 seconds – the time that will elapse from the moment the drivers meet until the moment the conductors meet.
Answer: 20 seconds