Question

Расстояние между пунктами А и В ( по железной дороге ) равно 420 км . Из А в В вышел скорый поезд со скоростью 60 км / ч . Через 2 часа навстречу ему из В в А вышел товарный поезд со скоростью 40 км / ч . Через сколько часов после выхода скорого поезда они встретятся ?

Answer 1

1)60*2=120км проехал поезд до выхода товарного поезда
2)420-120=300 км составляет расстояние между товарным и скорым
3)300:(60+40)=3 часа- через это время встретятся поезда, но учитывая,что скорый уже 2 часа в пути был, то время встречи-через 5 часов после выхода скорого поезда.

Answer 2

Problem Analysis

We are given the following information: - The distance between points A and B by rail is 420 km. - A fast train leaves point A towards point B at a speed of 60 km/h. - After 2 hours, a freight train leaves point B towards point A at a speed of 40 km/h.

We need to determine how many hours after the fast train leaves point A, the two trains will meet.

Solution

To solve this problem, we can use the formula:

Time = Distance / Speed

Let's calculate the time it takes for each train to travel the distance between points A and B.

The fast train travels at a speed of 60 km/h, so the time it takes to travel the distance of 420 km is:

Time for fast train = Distance / Speed = 420 km / 60 km/h

The freight train travels at a speed of 40 km/h, so the time it takes to travel the distance of 420 km is:

Time for freight train = Distance / Speed = 420 km / 40 km/h

Now, let's calculate the total time it takes for the two trains to meet. Since the freight train leaves 2 hours after the fast train, we need to add 2 hours to the time it takes for the freight train to travel the distance between points A and B.

Total time = Time for fast train + (Time for freight train + 2 hours)

Let's calculate the values:

Time for fast train = 420 km / 60 km/h = 7 hours

Time for freight train = 420 km / 40 km/h = 10.5 hours

Total time = 7 hours + (10.5 hours + 2 hours)

Now, let's calculate the total time:

Total time = 7 hours + (10.5 hours + 2 hours) = 7 hours + 12.5 hours = 19.5 hours

Therefore, the two trains will meet approximately 19.5 hours after the fast train leaves point A.

Answer

The two trains will meet approximately 19.5 hours after the fast train leaves point A.