Question

Из города А в город Б вышел поезд со скоростью 80км/ч. Через 2 часа из города Б ему навстречу вышел поезд со скоростью 90км/ч. Через сколько часов после выхода второго поезда они встретились, если расстояние между городами 500 км?

Answer 1

Скорость 1 поезда 80 км/ч

Скорость 2 поезжа 90 км/ч

 

80*2=160 км прошел 1 поезд

500-160=340 км между ними

340:(80+90)=340:170=2 ч. встретятся

Answer 2

Problem Analysis

We are given that a train travels from City A to City B at a speed of 80 km/h, and after 2 hours, another train starts from City B towards City A at a speed of 90 km/h. We need to determine how many hours it takes for the two trains to meet if the distance between the cities is 500 km.

Solution

Let's assume that it takes x hours for the two trains to meet.

In the first 2 hours, the first train from City A would have traveled a distance of 80 km/h * 2 h = 160 km.

The remaining distance between the two trains is 500 km - 160 km = 340 km.

Since the two trains are moving towards each other, their combined speed is 80 km/h + 90 km/h = 170 km/h.

To find the time it takes for the two trains to meet, we can use the formula:

time = distance / speed.

Substituting the values, we have:

x = 340 km / 170 km/h = 2 hours.

Therefore, it takes 2 hours for the two trains to meet after the second train starts its journey.

Answer

The two trains will meet after 2 hours from the time the second train starts its journey.

Explanation

After the first train travels for 2 hours, it covers a distance of 160 km. The remaining distance between the two trains is 340 km. Since the two trains are moving towards each other, their combined speed is 170 km/h. Using the formula time = distance / speed, we find that it takes 2 hours for the two trains to meet.