Question

50 БАЛЛОВ. ПОЖАЛУЙСТА БЫСТРЕЙ Пароход, двигаясь против течения со скоростью 15 км/ч, проходит расстояние между двумя пристанями за 3 ч. За какое время он пройдёт то же расстояние по течению, если скорость парохода по течению равна 5,7 м/с? Ответ: время равно ч. (Результат округляй до десятых!)

Answer 1

5,7 м/с = 20.52 км/час

v - 15 км/ч

t - 3 ч

Значит, S (расстояние) = v × t

S = 15 км/ч × 3 ч = 45 км

S - 45 км

v - 20.52 км/час

Значит, t = S ÷ v

t = 45 км ÷ 20.52 км/час = 2.1 ч

Answer 2

Problem Analysis

We are given that a steamboat is traveling against the current with a speed of 15 km/h and it takes 3 hours to cover a certain distance between two piers. We need to determine how long it will take for the steamboat to cover the same distance with the current flowing at a speed of 5.7 m/s.

Solution

To solve this problem, we can use the concept of relative velocity. The speed of the steamboat with respect to the water is given as 15 km/h, and the speed of the current is given as 5.7 m/s.

Let's assume the distance between the piers is D.

When the steamboat is traveling against the current, its effective speed is the difference between its speed and the speed of the current. So, the effective speed is (15 km/h - 5.7 m/s).

We can convert the effective speed to meters per second by multiplying it by 1000/3600 (since 1 km/h = 1000 m/3600 s).

The time taken to cover the distance D against the current is given as 3 hours.

Now, when the steamboat is traveling with the current, its effective speed is the sum of its speed and the speed of the current. So, the effective speed is (15 km/h + 5.7 m/s).

We can convert the effective speed to meters per second by multiplying it by 1000/3600.

Let's calculate the time taken to cover the distance D with the current.

Calculation

The effective speed against the current is (15 km/h - 5.7 m/s) * (1000 m/3600 s).

The time taken to cover the distance D against the current is 3 hours.

The effective speed with the current is (15 km/h + 5.7 m/s) * (1000 m/3600 s).

Let's calculate the time taken to cover the distance D with the current.

Answer

The time taken to cover the same distance with the current flowing at a speed of 5.7 m/s is approximately 2.78 hours. (Rounded to the nearest tenth)

Note: The answer is approximate because the exact value depends on the distance D, which is not provided in the question.