Question

Расстояние между двумя пунктами 12 км. Из них одновременно навстречу друг другу выехали два велосипедиста со скоростью 10 км/ч и 8км/ч. Каждый из них доехал до другого пункта,повернул и поехал назад с той же скоростью. Через сколько часов после начала движения они встретятся во второй раз?

Answer 1

12*2=24км -надо всего проехать
10+8=18 км/ч-общая скорость
24/18=1целая6/18=1  1/3часов они встретятся

Answer 2

Problem Analysis

We have two cyclists who start simultaneously from two points that are 12 km apart. Each cyclist rides towards the other point at speeds of 10 km/h and 8 km/h, respectively. When they reach the other point, they turn around and ride back at the same speed. We need to determine how many hours it will take for them to meet for the second time.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed between the two cyclists is the sum of their individual speeds. In this case, the relative speed is 10 km/h + 8 km/h = 18 km/h.

The time it takes for the two cyclists to meet for the first time is equal to the distance between the two points divided by their relative speed. In this case, the distance is 12 km and the relative speed is 18 km/h, so the time it takes for them to meet for the first time is 12 km / 18 km/h = 2/3 hours.

After they meet for the first time, each cyclist turns around and rides back to their starting point. The time it takes for each cyclist to return to their starting point is the same as the time it took for them to meet for the first time, which is 2/3 hours.

Therefore, the total time it takes for them to meet for the second time is twice the time it took for them to meet for the first time, which is 2 * (2/3) = 4/3 hours.

Answer

The two cyclists will meet for the second time after 4/3 hours.

Explanation

Let's break down the solution step by step:

1. The relative speed between the two cyclists is the sum of their individual speeds, which is 10 km/h + 8 km/h = 18 km/h. 2. The time it takes for the two cyclists to meet for the first time is equal to the distance between the two points divided by their relative speed. In this case, the distance is 12 km and the relative speed is 18 km/h, so the time is 12 km / 18 km/h = 2/3 hours. 3. After they meet for the first time, each cyclist turns around and rides back to their starting point. The time it takes for each cyclist to return to their starting point is the same as the time it took for them to meet for the first time, which is 2/3 hours. 4. Therefore, the total time it takes for them to meet for the second time is twice the time it took for them to meet for the first time, which is 2 * (2/3) = 4/3 hours.

Please let me know if anything is unclear or if you need further assistance!