Question

автомобилист проехал первую половину пути со скорость в 8 раз больше , чем вторую. Поэтому, средняя скорость автомобилиста равна 30 км.ч. Определить скорость автомобилиста на 2ой половине пути.

Answer 1

Ответ:

дано : V1=8V2, S1=S2, VCP=16км/ч формула VCP=[S1+S2]/(t1+t2), t1=S1/V1=S1/8V2 ,t2=S2/V2=S1/V2.Тогда подставим :16=(S1+S1)/(S1/8V2+S1/V2)=2/(1/8V2+1/V2)=2*8V2/9, V2=9км/ч. V1=8*9=72км/ч.

Answer 2

Problem Analysis

We are given that a driver traveled the first half of the distance with a speed 8 times greater than the speed of the second half. The average speed of the driver is given as 30 km/h. We need to determine the speed of the driver during the second half of the journey.

Solution

Let's assume the speed of the driver during the second half of the journey is x km/h.

To find the speed during the first half, we can use the given information that the driver's speed during the first half is 8 times greater than the speed during the second half. Therefore, the speed during the first half is 8x km/h.

The average speed of the driver is given as 30 km/h. We can use the formula for average speed, which is the total distance divided by the total time. Since the distance for both halves is the same, we can write:

Average Speed = (Total Distance) / (Total Time)

The total distance is the sum of the distances traveled during the first and second halves. Let's assume the total distance is d km. Therefore, the distance traveled during each half is d/2 km.

The total time is the sum of the times taken during the first and second halves. The time taken is equal to the distance divided by the speed. Therefore, the time taken during the first half is (d/2) / (8x) hours and the time taken during the second half is (d/2) / x hours.

Substituting these values into the average speed formula, we get:

30 = (d/2 + d/2) / ((d/2) / (8x) + (d/2) / x)

Simplifying the equation, we get:

30 = (d/2) * (8x + x) / (d/2 + d/2)

Simplifying further, we get:

30 = (9x) / 2

Solving for x, we find:

x = (30 * 2) / 9 = 6.67 km/h

Therefore, the speed of the driver during the second half of the journey is approximately 6.67 km/h.

Answer

The speed of the driver during the second half of the journey is approximately 6.67 km/h.