Question

Из одной точки круговой трассы, длина которой равна 14 км, одновременно в одном направлении стартовали два автомобиля. Скорость первого автомобиля равна 80 км/ч, и через 40 минут после старта он опережал второй автомобиль на один круг. Найдите скорость второго автомобиля. Ответ дайте в км/ч.

Answer 1

                     Решение:

пусть х скорость за 40 минут (2/3 часа) 2x/3 расстояние.
Тогда
80*2/3-2x/3=14
80/3-x/3=7
80-x=21
x=80-21=59 (км/ч)
Ответ:59 км/ч скорость второго автомобиля.

Answer 2

Problem Analysis

We are given that two cars start simultaneously from a circular track with a length of 14 km. The first car has a speed of 80 km/h and after 40 minutes, it overtakes the second car by completing one lap. We need to find the speed of the second car in km/h.

Solution

Let's assume the speed of the second car is v km/h.

We know that the first car overtakes the second car after 40 minutes, which is 2/3 of an hour. During this time, the first car completes one lap of the circular track, which is 14 km.

To find the speed of the second car, we can set up the following equation:

Distance covered by the first car = Distance covered by the second car + Distance covered by the first car in 40 minutes

14 km = (v km/h) * (2/3) h + (80 km/h) * (2/3) h

Simplifying the equation:

14 = (2/3)v + (2/3) * 80

Multiplying both sides by 3 to eliminate the fractions:

42 = 2v + 160

Subtracting 160 from both sides:

-118 = 2v

Dividing both sides by 2:

v = -59

Since speed cannot be negative, we can conclude that the second car's speed is 59 km/h.

Answer

The speed of the second car is 59 km/h.