Question

Два поезда одновременно отправились то одной станции в противоположных направлениях . Через 2 ч. расстояние между ними стало 280км. С какой средней скоростью двигались каждый поезд, если у первого поезда она была на 20км\ч. больше , чем у второго ?

Answer 1

Х км/ч - скорость ІІ поезда(х+20) км/ч - скорость ІІ поездах+х+20=280:22х=120х=60(км.ч) - скорость ІІ поезда60+20=80(км/ч) - скорость І поезда Арифметический способ:280:2=140(км/ч) - скорость отдаления поездов140-20=120(км/ч) - сумма двух одинаковых скоростей120:2=60(км/ч) - скорость ІІ поезда60+20=80(км/ч) - скорость І поезда

Answer 2

Problem Analysis

We have two trains that start simultaneously from the same station in opposite directions. After 2 hours, the distance between them is 280 km. We need to find the average speed of each train, given that the speed of the first train is 20 km/h greater than the speed of the second train.

Solution

Let's assume the speed of the second train is x km/h. Then the speed of the first train would be x + 20 km/h.

We can use the formula distance = speed × time to calculate the distance traveled by each train in 2 hours.

For the first train: distance = (speed of the first train) × (time) = (x + 20) × 2 = 2x + 40 km

For the second train: distance = (speed of the second train) × (time) = x × 2 = 2x km

According to the problem, the distance between the two trains after 2 hours is 280 km. So we can set up the following equation:

(distance traveled by the first train) + (distance traveled by the second train) = 280

(2x + 40) + 2x = 280

Simplifying the equation:

4x + 40 = 280

4x = 240

x = 60

Therefore, the speed of the second train is 60 km/h, and the speed of the first train is 60 + 20 = 80 km/h.

Answer

The second train was moving at an average speed of 60 km/h, while the first train was moving at an average speed of 80 km/h.