Question

Из Москвы и Киева одновременно вышли на встречу друг другу два товарных поезда. Первый поезд проходил 38км в час, а второй 40км в час. На каком расстоянии от Киева поезда встретятся? Расстояние между Москвой и Киевом 858км.​

Answer 1

Ответ: поезда встретятся через 11 часов.

Пошаговое объяснение:

1) 38+40=78 ( км/ч ) - общая скорость поездов.

2) 858:78=11 часов

Answer 2

Problem Analysis

We are given that two freight trains leave Moscow and Kyiv simultaneously to meet each other. The first train travels at a speed of 38 km/h, while the second train travels at a speed of 40 km/h. We need to determine the distance from Kyiv where the trains will meet. The distance between Moscow and Kyiv is given as 858 km.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed of the two trains is the sum of their individual speeds. In this case, the relative speed is 38 km/h + 40 km/h = 78 km/h.

Let's assume that the trains meet after traveling a distance of x km from Kyiv. The first train will have traveled a distance of (858 - x) km from Moscow.

We can use the formula: time = distance / speed to calculate the time taken by each train to reach the meeting point.

The time taken by the first train is: time1 = (858 - x) / 38 hours.

The time taken by the second train is: time2 = x / 40 hours.

Since the trains leave simultaneously and meet at the same time, the two times are equal. Therefore, we can set up the equation:

(858 - x) / 38 = x / 40

To solve this equation, we can cross-multiply and simplify:

40 * (858 - x) = 38 * x

34320 - 40x = 38x

78x = 34320

x = 34320 / 78

x ≈ 439.487 km

Therefore, the trains will meet approximately 439.487 km from Kyiv.

Answer

The trains will meet at a distance of approximately 439.487 km from Kyiv.