Question

Моторная лодка по течению реки двигалась со скоростью 12км/ч и расстояние от пристани А до пристани В прошла за 40 мин.Сколько минут она будет двигатся в обратном направлении,если скорость течения равна 1км/ч?

Answer 1

12 * 2/3 = 8 км ( расстояние)
12 - 1 = 11 ( собст. скорость лодки)
11-1= 10 ( скорость лодки против течения)
8 : 10 = 8/10 часа = 48 минут
Ответ: 48 минут.

Answer 2

Calculation of Time for the Return Journey

To calculate the time it will take for the motorboat to travel in the opposite direction, we need to consider the speed of the boat and the speed of the river current.

Given information: - Speed of the motorboat: 12 km/h - Distance from point A to point B: unknown - Time taken to travel from point A to point B: 40 minutes - Speed of the river current: 1 km/h

To find the distance from point A to point B, we can use the formula:

Distance = Speed x Time

Converting the time from minutes to hours (40 minutes = 40/60 = 2/3 hours), we can calculate the distance:

Distance = 12 km/h x 2/3 hours

Simplifying the calculation:

Distance = 8 km

Now that we know the distance, we can calculate the time it will take for the motorboat to travel in the opposite direction. The speed of the river current is subtracted from the speed of the motorboat because it is moving in the opposite direction.

Let's denote the time for the return journey as T.

Distance = (Speed of the motorboat - Speed of the river current) x Time

Substituting the known values:

8 km = (12 km/h - 1 km/h) x T

Simplifying the equation:

8 km = 11 km/h x T

To solve for T, we divide both sides of the equation by 11 km/h:

T = 8 km / 11 km/h

Simplifying the calculation:

T = 8/11 hours

Converting the time back to minutes:

T = (8/11) x 60 minutes

Simplifying the calculation:

T ≈ 43.64 minutes

Therefore, the motorboat will take approximately 43.64 minutes to travel in the opposite direction.

Please note that the calculated time is an approximation and may vary slightly depending on the exact values used.