Question

Поезд двигался первую половину времени со скоростью 60 км\ч, а вторую - 40 км\ч. определите среднюю скорость на всем пути. (ответ должен быть 48 км/ч, но мне нужно решение. и распишите все подробно с объяснением, пожалуйста) даю 20 баллов

Answer 1

Дано t1=t2=t/2   Vср- ?

Vср=(S1+S2)/t=(V1*t/2  +V2*t/2)/t=(V1+V2)/2=100/2=50 км/ч

чтобы получить 48 нужно другое условие
S1=S2=S/2
Vср=S/(t1+t2)=S/(S/2*V1+S/2*V2)=2*V1*V2(V1+V2)=48 км/ч

Answer 2

Calculating Average Speed of a Train

To calculate the average speed of the train, we can use the formula:

Average Speed = Total Distance / Total Time

First, let's calculate the total distance traveled by the train.

The train moved for the first half of the time at a speed of 60 km/h and for the second half at a speed of 40 km/h.

Let's assume the total time taken by the train is t hours. Therefore, the train traveled at 60 km/h for t/2 hours and at 40 km/h for t/2 hours.

The total distance traveled can be calculated as:

Total Distance = (60 km/h) * (t/2) + (40 km/h) * (t/2)

Simplifying this expression gives us the total distance in terms of t.

Now, let's calculate the total time taken by the train.

The total time taken is simply t hours.

Now, we can use the formula for average speed to find the average speed of the train.

Calculation

The average speed of the train is given by:

Average Speed = Total Distance / Total Time

Substituting the expressions for total distance and total time, we get:

Average Speed = (60 km/h * t/2 + 40 km/h * t/2) / t

Simplifying this expression will give us the average speed of the train in terms of t.

Let's proceed with the calculation.