Question

o Два поїзди виїхали з однієї станції в одному напрямі. Швидкість пер- шого поїзда 72 км/год, що становить 80% швидкості другого поїзда. Другий поїзд виїхав на 2,5 год пізніше від першого. Через який час він наздогнав перший поїзд? На якій відстані один від одного були поїзди через 4 год після виходу другого поїзда? Через 15 год після виходу другого поїзда?​

Answer 1

Ответ:

Пошаговое объяснение:

72:0,8=90 км/год швидк 2 поезда

72×2,5=180км проехал 1 поезд за 2,5 год

90×4=360км проехал 2 поезд за 4 год

72×6,5=468км проехал 1 поезд за 4 год после выхода 2 поезда

90×15=1350км проехал 2 поезд за 15 год

72×17,5=1260км проехал 1 поезд за 15 год после выхода 2 поезда

1350-1260=90км между ними через 15 год

Значит через 14 год 2 поезд Догонит 1

Answer 2

To solve this problem, we need to find the time it takes for the second train to catch up with the first train and the distance between the two trains at different time intervals.

Given Information:

- Speed of the first train: 72 km/h - Speed of the second train: 80% of the speed of the first train - The second train departs 2.5 hours later than the first train

Time it takes for the second train to catch up with the first train:

Let's assume that the time it takes for the second train to catch up with the first train is t hours.

Since the second train departs 2.5 hours later than the first train, the first train has already traveled for t + 2.5 hours when the second train starts.

The distance traveled by the first train is given by the formula: distance = speed × time.

Therefore, the distance traveled by the first train is: 72 × (t + 2.5).

The distance traveled by the second train is: 0.8 × 72 × t (since the second train's speed is 80% of the first train's speed).

For the second train to catch up with the first train, the distances traveled by both trains should be equal. Therefore, we can set up the following equation:

72 × (t + 2.5) = 0.8 × 72 × t

Simplifying the equation, we get:

72t + 180 = 57.6t

Solving for t, we find:

14.4t = 180

t = 180 / 14.4

t ≈ 12.5 hours

Therefore, it takes approximately 12.5 hours for the second train to catch up with the first train.

Distance between the two trains after 4 hours:

To find the distance between the two trains after 4 hours, we can substitute t = 4 into the equation we derived earlier:

distance = 72 × (t + 2.5)

distance = 72 × (4 + 2.5)

distance ≈ 72 × 6.5

distance ≈ 468 km

Therefore, after 4 hours, the two trains are approximately 468 km apart.

Distance between the two trains after 15 hours:

To find the distance between the two trains after 15 hours, we can substitute t = 15 into the equation we derived earlier:

distance = 72 × (t + 2.5)

distance = 72 × (15 + 2.5)

distance ≈ 72 × 17.5

distance ≈ 1260 km

Therefore, after 15 hours, the two trains are approximately 1260 km apart.

Please note that the calculations provided are approximate and may vary slightly.