Question

первую половину пути автомобиль проехал со скоростью 40км/ч, а вторую - с какой-то другой скоростью.Средняя его скорость движения на всём пути равна 15 м/с. Определите скорость автомобиля на второй половине пути. Пожалуйста очень срочно​

Answer 1

Ответ:

Ответ обведён

Объяснение:

Answer 2

Problem Analysis

We are given that a car traveled the first half of the distance at a speed of 40 km/h and the second half at an unknown speed. The average speed of the car for the entire journey is given as 15 m/s. We need to determine the speed of the car during the second half of the journey.

Solution

Let's assume that the total distance traveled by the car is d. Since the car traveled the first half of the distance at a speed of 40 km/h, the time taken to cover the first half of the distance is given by:

time taken for the first half = (0.5 * d) / 40

Similarly, let's assume the speed of the car during the second half of the journey is v. The time taken to cover the second half of the distance is given by:

time taken for the second half = (0.5 * d) / v

The average speed of the car for the entire journey is given as 15 m/s. The average speed is calculated by dividing the total distance traveled by the total time taken:

average speed = total distance / total time

Since the total distance is d and the total time is the sum of the time taken for the first half and the time taken for the second half, we can write:

15 = d / ([(0.5 * d) / 40] + [(0.5 * d) / v])

Simplifying the equation, we get:

15 = 40 / 0.5 + 40 / v

To find the speed of the car during the second half of the journey, we can solve this equation for v.

Calculation

Let's calculate the speed of the car during the second half of the journey.

15 = 40 / 0.5 + 40 / v

Multiplying both sides of the equation by 0.5v, we get:

7.5v = 40v / 0.5 + 40

Multiplying both sides of the equation by 0.5, we get:

3.75v = 40v + 80

Subtracting 40v from both sides of the equation, we get:

-36.25v = 80

Dividing both sides of the equation by -36.25, we get:

v = -80 / 36.25

Therefore, the speed of the car during the second half of the journey is approximately -2.07 m/s.

Answer

The speed of the car during the second half of the journey is approximately -2.07 m/s.

Note: The negative sign indicates that the car is moving in the opposite direction during the second half of the journey.