Question

Расстояние между причалами 120 километров собственная скорость теплохода 25 километров час если теплоход плывет вниз по реке то это расстояние он преодолевает за 4 часа найдите скорость течения реки время за которое теплоход преодолевает это расстояние вверх по реке против ее течения

Answer 1

120:4=30 км\ч скорость по течению
30-25=5 км\ч скорость течения
25-5=20 скорость против течения 
120:20=6 ч время за которое теплоход преодолевает это расстояние ротив течения реки
ответ: 6ч и 5 км\ч

Answer 2

Problem Analysis

We are given the following information: - Distance between piers: 120 kilometers - Speed of the ship: 25 kilometers per hour - Time taken to travel downstream: 4 hours

We need to find: - Speed of the river current - Time taken to travel upstream against the current

Downstream Calculation

When the ship is traveling downstream, it benefits from the speed of the river current. The effective speed of the ship is the sum of its own speed and the speed of the current. We can use the formula:

Effective speed downstream = Ship speed + River current speed

Given that the distance is 120 kilometers and the time taken is 4 hours, we can use the formula:

Distance = Speed × Time

To find the effective speed downstream, we rearrange the formula:

Effective speed downstream = Distance / Time

Substituting the given values:

Effective speed downstream = 120 km / 4 hours = 30 km/h

Since the effective speed downstream is the sum of the ship speed and the river current speed, we can write the equation:

30 km/h = 25 km/h + River current speed

Simplifying the equation:

River current speed = 30 km/h - 25 km/h = 5 km/h

Therefore, the speed of the river current is 5 km/h.

Upstream Calculation

When the ship is traveling upstream against the current, it faces resistance from the river current. The effective speed of the ship is the difference between its own speed and the speed of the current. We can use the formula:

Effective speed upstream = Ship speed - River current speed

We know that the distance between the piers is 120 kilometers. Let's assume the time taken to travel upstream is t hours.

Using the formula Distance = Speed × Time, we can write the equation:

Distance = Effective speed upstream × Time

Substituting the known values:

120 km = (25 km/h - 5 km/h) × t hours

Simplifying the equation:

120 km = 20 km/h × t hours

Solving for t:

t = 120 km / 20 km/h = 6 hours

Therefore, the time taken to travel upstream against the current is 6 hours.

To summarize: - The speed of the river current is 5 km/h. - The time taken to travel upstream against the current is 6 hours.

Please let me know if I can help you with anything else.