Question

Моторная лодка путь от одной пристани до другой проходит за 4ч а обратный путь за 5ч. какова скорость лодки в стоячей воде если 70км по течению она проходит за 3,5 ч

Answer 1

Пусть скорость лодки в стоячей воде Х км/ч, а скорость течения у км/ч, значит
《4×(Х+У)=5×(Х-У) 《4Х+4У=5ХУ
《3,5×(Х+У)=70 《Х+У=20


《9У=Х 《У=2
《10У=20 《Х=18
ОТВЕТ: СКОРОСТЬ ЛОДКИ В СТОЯЧЕЙ ВОДЕ 18 КМ/Ч

Answer 2

Calculation of Boat Speed in Still Water

To calculate the speed of the boat in still water, we can use the concept of relative speed. The boat's speed in still water can be determined by subtracting the speed of the current from the boat's speed when traveling with the current and adding the speed of the current to the boat's speed when traveling against the current.

Let's denote the boat's speed in still water as x km/h and the speed of the current as y km/h.

Given the following information: - The boat takes 4 hours to travel from one dock to another. - The boat takes 5 hours to travel back from the second dock to the first dock. - The boat takes 3.5 hours to travel 70 km with the current.

We can set up the following equations:

1. When traveling from the first dock to the second dock: - Distance = Speed × Time - (x + y) × 4 = Distance

2. When traveling from the second dock to the first dock: - Distance = Speed × Time - (x - y) × 5 = Distance

3. When traveling with the current: - Distance = Speed × Time - (x + y) × 3.5 = 70

To find the values of x and y, we can solve these equations simultaneously.

Let's solve the equations step by step:

1. From equation 3, we have: - (x + y) × 3.5 = 70 - x + y = 20 2. From equation 1, we have: - (x + y) × 4 = Distance - (x + y) × 4 = (x - y) × 5 - 4x + 4y = 5x - 5y - x = 9y Substituting the value of x from equation 2 into equation 1, we have: - 9y + y = 20 - 10y = 20 - y = 2

Substituting the value of y into equation 2, we have: - x = 9(2) - x = 18

Therefore, the speed of the boat in still water is 18 km/h and the speed of the current is 2 km/h.

Please note that the calculations are based on the given information and assumptions.