Question

Плот и лодка движутся навстречу друг другу по реке.Они находятся на расстоянии 20 км друг от друга. Через какое время они встретятся, если собственная скорость лодки 8 км в час, а скорость течения реки 2 км в час.

Answer 1

Плот может двигаться только по течению.значит его скорость 2 км/ч. Скорость лодки против течения 8-2=6 км/ч
6+2=8 км/ч скорость сближения
20:8=2,5 ч встретятся

Answer 2

Problem Analysis

We are given that a boat and a raft are moving towards each other on a river. The boat's speed is 8 km/h, and the river's current speed is 2 km/h. We need to determine how long it will take for them to meet.

Solution

To solve this problem, we can use the concept of relative velocity. The relative velocity is the difference between the velocities of two objects moving in the same direction or opposite directions.

Let's assume that the boat and the raft meet after time 't'. During this time, the boat will cover a distance of 8t km, and the raft will cover a distance of 2t km (since the river's current speed is 2 km/h).

Since they are moving towards each other, the total distance covered by both the boat and the raft will be equal to the initial distance between them, which is 20 km.

Therefore, we can write the equation: 8t + 2t = 20

Simplifying the equation: 10t = 20 t = 2

So, it will take 2 hours for the boat and the raft to meet.

Answer

The boat and the raft will meet after 2 hours.

Explanation

When the boat and the raft are moving towards each other, the boat's speed is 8 km/h, and the river's current speed is 2 km/h. Using the concept of relative velocity, we can determine that it will take 2 hours for them to meet. During this time, the boat will cover a distance of 16 km (8 km/h * 2 h), and the raft will cover a distance of 4 km (2 km/h * 2 h). The total distance covered by both the boat and the raft will be equal to the initial distance between them, which is 20 km.