Question

Расстояние между пристанями А и В равно 18 км. Из А в В по точению реки отправился плот, а через 30 мин за ним отправилась моторная лодка, которая, прибыла в пункт В тотчас повернула обратно и возвратилась в пункт А. к этому времени плот прошел 9км. Найдите скорость лодки в стоячей воде, если скорость течения реки равна 50м/мин

Answer 1

Скорость течения равна скорости плота, значит время плота =9000/50=180 минут, время лодки на 30 мин меньше, зн 180-30=160, скорость лодки (1800+1800)/160=225 - здесь скорость течения не учитывается, так как самоуничтожается

Answer 2

Problem Analysis

To solve this problem, we need to find the speed of the motorboat in still water. We are given that the distance between the docks A and B is 18 km, the speed of the river's current is 50 m/min, and the raft has traveled 9 km by the time the motorboat reaches point B and returns to point A.

Calculating the Speed of the Motorboat

Let's denote the speed of the motorboat in still water as x. The speed of the current is given as 50 m/min.

When the motorboat travels from A to B, the effective speed is the sum of the speed of the motorboat and the speed of the current. When it returns from B to A, the effective speed is the difference between the speed of the motorboat and the speed of the current.

The time taken for the motorboat to travel from A to B and back to A is the same. We can use the formula: time = distance / speed.

Let's calculate the speed of the motorboat using the given information.

Solution

The speed of the motorboat in still water can be calculated using the following steps:

1. Calculate the time taken for the motorboat to travel from A to B and back to A. 2. Use the time and the distance traveled by the raft to find the speed of the motorboat.

The time taken for the motorboat to travel from A to B and back to A is the same. Let's denote this time as t.

The time taken for the raft to travel 9 km is 30 minutes, and the speed of the river's current is 50 m/min. We can use this information to calculate the time taken for the motorboat to travel from A to B and back to A.

The speed of the motorboat in still water can be calculated using the formula: speed = distance / time.

Let's proceed with the calculations.