Question

Мальчик шёл со скоростью 5 км/ч ,через час бабушка поехала догонять его со скоростью 10 км/ч .За какое время она его догонит

Answer 1

За час мальчик прошёл 5 км,
за второй час он пройдет 10 км, а бабушка проедет 10 км.
Ответ: бабушка догонит его через час

Answer 2

Problem Analysis

We are given that a boy is walking at a speed of 5 km/h, and after an hour, his grandmother starts driving to catch up with him at a speed of 10 km/h. We need to determine how long it will take for the grandmother to catch up with the boy.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed is the difference between the speeds of two objects moving in the same direction. In this case, the relative speed between the boy and his grandmother is 10 km/h - 5 km/h = 5 km/h.

To find the time it takes for the grandmother to catch up with the boy, we can use the formula:

Time = Distance / Speed

The distance the grandmother needs to cover to catch up with the boy is the same as the distance the boy has already covered in one hour, which is 5 km.

Substituting the values into the formula, we get:

**Time = 5 km / 5 km/h = 1