Question

Два друга -охотника вышли навстречу друг другу из леса с двух сторон поляны на расстоянии 450 м друг от друга,Один шел со скоростью 70 м \мин, а другой со скоростью 80 м\мин собака бегала между ними ,какое расстояние она пробежала ,если она бегала со скоростью 12 км \час.

Answer 1

70+80=150м/мин-скорость сближения охотников
450/150=3мин-через сколько они встретились

12км/ч *1000 м/км=12000 м/ч
12000 м/ч :60 мин/ч=12000м/ч*1/60ч/мин=200м/мин-скорость собаки

200*3=600м пробежала собака

Answer 2

Problem Setup

Two friends, both hunters, are walking towards each other from opposite sides of a clearing in the forest. They are 450 meters apart. One friend walks at a speed of 70 m/min, and the other walks at a speed of 80 m/min. A dog runs back and forth between them at a speed of 12 km/h.

Calculating the Distance Covered by the Dog

To find the distance the dog covered, we can use the concept of relative speed. The relative speed of the two friends is the sum of their individual speeds, as they are moving towards each other. The relative speed of the dog with respect to the two friends is the difference between the speed of the faster friend and the speed of the slower friend.

Solution

Using the relative speed concept, we can calculate the distance covered by the dog.

The relative speed of the two friends is 70 m/min + 80 m/min = 150 m/min.

Converting the dog's speed to m/min: 12 km/h = 12000 m/h = 12000 m/60 min = 200 m/min.

The relative speed of the dog with respect to the two friends is 200 m/min - 150 m/min = 50 m/min.

Now, we can use the formula: distance = speed × time.

Let's denote the distance covered by the dog as D.

The time taken for the two friends to meet each other is the time it takes for them to cover the initial distance of 450 meters. We can use the formula: time = distance / speed.

For the first friend: time = 450 m / 70 m/min = 6.43 min.

For the second friend: time = 450 m / 80 m/min = 5.63 min.

The time taken for the two friends to meet each other is approximately 5.63 minutes.

Now, we can calculate the distance covered by the dog: D = speed × time = 50 m/min × 5.63 min ≈ 281.5 meters.

Answer

The dog covered approximately 281.5 meters while running back and forth between the two friends.