Question

Лодка держит курс перпендикулярно берегу и движется со скоростью 7, 2 км/ч .Течение относит ее на расстоЯние 150м вниз по реке.Найдите скорость течения реки и время затраченное на переезд через реку. Ширина реки равна 0, 5 км Помогите срочно, за пол часа

Answer 1

Скорость лодки
Vл = 7,2 км/ч = 2 м/с
Ширина реки
Sp = 0,5 км = 500 м
Время движения:
t = Sp/Vл = 500/2 = 250 c
Sс = 150 м  - снос лодки

Скорость реки:

Vp = Sc/t= 150/250 = 0,6 м/с
 или приблизительно 2,2 км/ч

Answer 2

Problem Analysis

We are given the following information: - The boat is moving perpendicular to the shore with a speed of 7.2 km/h. - The current carries the boat downstream a distance of 150 m. - The width of the river is 0.5 km.

We need to find: - The speed of the river current. - The time taken to cross the river.

To solve this problem, we can use the concept of relative velocity.

Solution

Let's assume the speed of the river current is v km/h.

The boat's velocity relative to the ground is the vector sum of its velocity relative to the water and the velocity of the water relative to the ground.

The velocity of the boat relative to the water is given as 7.2 km/h.

The velocity of the water relative to the ground is the speed of the river current, v km/h.

Therefore, the velocity of the boat relative to the ground is the vector sum of 7.2 km/h and v km/h.

To find the time taken to cross the river, we need to calculate the distance traveled by the boat perpendicular to the shore.

Let's denote the time taken to cross the river as t hours.

The distance traveled by the boat perpendicular to the shore is the product of the boat's velocity relative to the ground and the time taken to cross the river.

The distance traveled by the boat perpendicular to the shore is also equal to the width of the river, which is 0.5 km.

Using the above information, we can set up the following equation:

7.2 km/h + v km/h = 0.5 km / t hours

Simplifying the equation, we get:

7.2 + v = 0.5 / t

To find the speed of the river current, we need to solve this equation for v.

Let's solve the equation:

7.2 + v = 0.5 / t

v = 0.5 / t - 7.2

Now, we can substitute the value of v in terms of t into the equation for the distance traveled by the boat perpendicular to the shore:

7.2 + (0.5 / t - 7.2) = 0.5

Simplifying the equation, we get:

0.5 / t = 0.5

Solving for t, we find:

t = 1 hour

Therefore, the time taken to cross the river is 1 hour.

Now, we can substitute the value of t into the equation for v:

v = 0.5 / 1 - 7.2

Simplifying the equation, we get:

v = -6.7 km/h

Since the speed of the river current cannot be negative, we can conclude that there is an error in the given information or calculations.

Please double-check the given information and calculations to ensure accuracy.

If you have any further questions, feel free to ask.