Question

Помогите, срочно расстояние между двумя пристанями катер прошёл по течению реки за 7 часов , а против за 8 часов, Найдите скорость течения реки если собственная скорость катера равна 21 км/ч

Answer 1

Ответ 1,4км/ч, решение на фото

Answer 2

Calculation of River Current Speed

To find the speed of the river current, we can use the formula:

Speed of the current = Distance / Time

Given that the boat took 7 hours to travel downstream (with the current) and 8 hours to travel upstream (against the current), we can set up the following equations:

Distance downstream = Speed of the boat + Speed of the current Distance upstream = Speed of the boat - Speed of the current

Let's solve these equations to find the speed of the river current.

1. Distance downstream = Speed of the boat + Speed of the current 2. Distance upstream = Speed of the boat - Speed of the current

Substituting the given values: 1. Distance downstream = 21 km/h + Speed of the current 2. Distance upstream = 21 km/h - Speed of the current

We can now solve these equations simultaneously to find the speed of the river current.

To solve the equations, we can use the method of substitution. We'll solve equation 1 for the distance downstream and substitute it into equation 2.

1. Distance downstream = 21 km/h + Speed of the current 2. (21 km/h + Speed of the current) - Speed of the current = Distance upstream

Simplifying equation 2: 2. 21 km/h = Distance upstream

Since the distance downstream is equal to the distance upstream, we can set the two equations equal to each other:

21 km/h = Distance upstream

Now we can solve for the speed of the river current.

Speed of the current = 21 km/h

Therefore, the speed of the river current is 21 km/h.