Question

1) Скорость моторной лодки в стоячей воде 15 км/ч, а скорость течения реки 3 км/ч. Сколько времени потратит моторная лодка на движение от одной пристани до другой и обратно, если расстояние между пристанями 36 км?

Answer 1

РЕШЕНИЕ
Время по течению
T1 = 36 : ( 15+3) = 36/18 = 2 ч -  время по течению
Время против течения.
Т2 = 36 : (15-3) = 36/12 = 3 ч - время против течения
Время в пути
2 +3 = 5 ч - ОТВЕТ

Answer 2

Calculation of Time Taken for Round Trip

To calculate the time taken for the motorboat to travel from one dock to another and back, we can use the formula: time = distance / speed.

Given: - Speed of the motorboat in still water = 15 km/h. - Speed of the river's current = 3 km/h. - Distance between the docks = 36 km.

First, we need to calculate the effective speed of the motorboat when moving with the current and against the current.

The effective speed of the motorboat when moving with the current: 15 km/h (boat's speed) + 3 km/h (current's speed) = 18 km/h.

The effective speed of the motorboat when moving against the current: 15 km/h (boat's speed) - 3 km/h (current's speed) = 12 km/h.

Now, we can calculate the time taken for the motorboat to travel from one dock to another and back.

Time taken downstream (with the current): 36 km (distance) / 18 km/h (effective speed) = 2 hours.

Time taken upstream (against the current): 36 km (distance) / 12 km/h (effective speed) = 3 hours.

Total time taken for the round trip: 2 hours (downstream) + 3 hours (upstream) = 5 hours.

Therefore, the motorboat will take 5 hours to travel from one dock to another and back.

I hope this helps! If you have further questions, feel free to ask.