Question

Два поезда выехали с одной и тойже станции одновременно в противоположных направлениях.один поезд движится со скоростью 60 км/ч, другой 90 км/ч.на каком расстоянии друг от друга окажутся поезда через 2 часа?через сколько времени расстояние между поездами будет 450 км?

Answer 1

60*2=120
90*2=180
180+120=300

отв: через 2 часа расстояние друг от друга окажется 300 км

90+60=150
450:150=3

отв: расстояние между поездами будет 450 через 3 часа.

Answer 2

С первым решением - все ясно - его уже опсали - 2часа.
Второе решение - это они движуться в одну сторону (т. е. поезд из А едет в противоположную от В сторону) , тогда 70 км между ними будет через:
(350-70)/(75-65)=28 часов.

Но есть и третье: после встречи поездов (в случае когда они едут друг на встречу другу) - они разьезжаются и тогда между ними снова будет 70 км через (350 плюс 70)/(75 плюс 65)=3 часа

Четвертое решение - когда один поезд обгоняет другой и через некоторое время между ними снова 70 км: (350 плюс 70)/(75-65)=42 часа - в практике вряд ли возможно - поскольку, если поезда едут в одну сторону, то они едут по одной рельсовой дороге. Хотя возможно для этого случая построят параллельную.

Answer 3

Problem Analysis

We have two trains that start from the same station simultaneously but in opposite directions. One train is moving at a speed of 60 km/h, and the other train is moving at a speed of 90 km/h. We need to find the distance between the trains after 2 hours and the time it takes for the distance between the trains to be 450 km.

Distance between the Trains after 2 Hours

To find the distance between the trains after 2 hours, we can use the formula: distance = speed * time.

For the first train, the speed is 60 km/h and the time is 2 hours. Therefore, the distance covered by the first train is 60 km/h * 2 hours = 120 km.

For the second train, the speed is 90 km/h and the time is 2 hours. Therefore, the distance covered by the second train is 90 km/h * 2 hours = 180 km.

Since the trains are moving in opposite directions, the distance between them is the sum of the distances covered by each train. Therefore, the distance between the trains after 2 hours is 120 km + 180 km = 300 km.

Time for the Distance between the Trains to be 450 km

To find the time it takes for the distance between the trains to be 450 km, we can set up the following equation:

distance = speed * time

Let's assume that the time it takes for the distance between the trains to be 450 km is t hours.

For the first train, the speed is 60 km/h, and the distance covered by the first train is 60 km/h * t hours = 60t km.

For the second train, the speed is 90 km/h, and the distance covered by the second train is 90 km/h * t hours = 90t km.

Since the trains are moving in opposite directions, the distance between them is the difference between the distances covered by each train. Therefore, the distance between the trains after t hours is 90t km - 60t km = 30t km.

We need to find the time t when the distance between the trains is 450 km. Therefore, we can set up the equation:

30t = 450

To solve for t, we divide both sides of the