Question

Помогите!!!! Очень прошу!!!! Отдаю последние баллы!!!! Первую треть трассы автомобиль ехал со скоростью 40 км/ч, вторую треть - со скоростью 60 км/ч, а последнюю - 120 км/ч. Найти среднюю скорость автомобиля на протяжении всего пути ?

Answer 1

Пусть х км весь путь,
тогда треть пути (первая, вторая, третья) равна (x/3)

при прямолинейном равномерном движении
ВРЕМЯ = РАССТОЯНИЕ : СКОРОСТЬ

тогда время пути на первой трети (x:3)/40=x/120 ч, на второй (x:3)/60=x/180 ч, на третьей (x:3)/120=x/360 ч.

СРЕДНЯЯ СКОРОСТЬ = (ПУТЬ 1+ ПУТЬ 2+ ПУТЬ 3) : (ВРЕМЯ1+ВРЕМЯ2+ВРЕМЯ3)

Значит его средняя скорость была
$\frac{x}{\frac{x}{120}+\frac{x}{180}+\frac{x}{360}}=$
$\frac{x}{\frac{3x}{360}+\frac{2x}{360}+\frac{x}{360}}=$
$x:\frac{3x+2x+x}{360}=x:\frac{6x}{360}=x:\frac{x}{60}$
$x*\frac{60}{x}=60$
ответ: 60 км\ч

Answer 2

Calculation of Average Speed

To find the average speed of the car over the entire distance, we need to calculate the total distance traveled and the total time taken.

Given that the car traveled the first third of the distance at a speed of 40 km/h, the second third at a speed of 60 km/h, and the last third at a speed of 120 km/h, we can assume that each third of the distance is equal.

Let's assume the total distance traveled is D km. Therefore, each third of the distance is D/3 km.

To calculate the total time taken, we need to find the time taken for each third of the distance and then sum them up.

The time taken for the first third of the distance is (D/3) / 40 hours.

The time taken for the second third of the distance is (D/3) / 60 hours.

The time taken for the last third of the distance is (D/3) / 120 hours.

Adding up these times will give us the total time taken.

To find the average speed, we divide the total distance traveled by the total time taken.

Let's calculate the average speed step by step:

1. Let's assume the total distance traveled is D km. 2. Each third of the distance is D/3 km. 3. The time taken for the first third of the distance is (D/3) / 40 hours. 4. The time taken for the second third of the distance is (D/3) / 60 hours. 5. The time taken for the last third of the distance is (D/3) / 120 hours. 6. The total time taken is (D/3) / 40 + (D/3) / 60 + (D/3) / 120 hours. 7. The average speed is D / [(D/3) / 40 + (D/3) / 60 + (D/3) / 120] km/h.

Now, let's calculate the average speed using the given information.

Calculation:

Let's assume the total distance traveled is D km.

The average speed of the car can be calculated using the formula:

Average Speed = Total Distance / Total Time

1. The car traveled the first third of the distance at a speed of 40 km/h. 2. The car traveled the second third of the distance at a speed of 60 km/h. 3. The car traveled the last third of the distance at a speed of 120 km/h.

Since each third of the distance is equal, we can assume that each third is D/3 km.

The time taken for the first third of the distance is (D/3) / 40 hours.

The time taken for the second third of the distance is (D/3) / 60 hours.

The time taken for the last third of the distance is (D/3) / 120 hours.

Adding up these times will give us the total time taken.

The average speed is then calculated as:

Average Speed = Total Distance / Total Time

Let's calculate the average speed step by step:

1. Let's assume the total distance traveled is D km. 2. Each third of the distance is D/3 km. 3. The time taken for the first third of the distance is (D/3) / 40 hours. 4. The time taken for the second third of the distance is (D/3) / 60 hours. 5. The time taken for the last third of the distance is (D/3) / 120 hours. 6. The total time taken is (D/3) / 40 + (D/3) / 60 + (D/3) / 120 hours. 7. The average speed is D / [(D/3) / 40 + (D/3) / 60 + (D/3) / 120] km/h.

Let's calculate the average speed using the given information:

1. The car traveled the first third of the distance at a speed of 40 km/h. 2. The car traveled the second third of the distance at a speed of 60 km/h. 3. The car traveled the last third of the distance at a speed of 120 km/h.

Since each third of the distance is equal, we can assume that each third is D/3 km.

The time taken for the first third of the distance is (D/3) / 40 hours.

The time taken for the second third of the distance is (D/3) / 60 hours.

The time taken for the last third of the distance is (D/3) / 120 hours.

Adding up these times will give us the total time taken.

The average speed is then calculated as:

Average Speed = Total Distance / Total Time

Let's calculate the average speed step by step:

1. Let's assume the total distance traveled is D km. 2. Each third of the distance is D/3 km. 3. The time taken for the first third of the distance is (D/3) / 40 hours. 4. The time taken for the second third of the distance is (D/3) / 60 hours. 5. The time taken for the last third of the distance is (D/3) / 120 hours. 6. The total time taken is (D/3) / 40 + (D/3) / 60 + (D/3) / 120 hours. 7. The average speed is D / [(D/3) / 40 + (D/3) / 60 + (D/3) / 120] km/h.

Now, let's calculate the average speed using the given information.

Calculation:

Let's assume the total distance traveled is D km.

The average speed of the car can be calculated using the formula:

Average Speed = Total Distance / Total Time

1. The car traveled the first third of the distance at a speed of 40 km/h. 2. The car traveled the second third of the distance at a speed of 60 km/h. 3. The car traveled the last third of the distance at a speed of 120 km/h.

Since each third of the distance is equal, we can assume that each third is D/3 km.

The time taken for the first third of the distance is (D/3) / 40 hours.

The time taken for the second third of the distance is (D/3) / 60 hours.

The time taken for the last third of the distance is (D/3) / 120 hours.

Adding up these times will give us the total time taken.

The average speed is then calculated as:

Average Speed = Total Distance / Total Time

Let's calculate the average speed step by step:

1. Let's assume the total distance traveled is D km. 2. Each third of the distance is D/3 km. 3. The time taken for the first third of the distance is (D/3) / 40 hours. 4. The time taken for the second third of the distance is (D/3) / 60 hours. 5. The time taken for the last third of the distance is (D/3) / 120 hours. 6. The total time taken is (D/3) / 40 + (D/3) / 60 + (D/3) / 120 hours. 7. The average speed is D / [(D/3) / 40 + (D/3) / 60 + (D/3) / 120] km/h.

Now, let's calculate the average speed using the given information.

Calculation:

Let's assume the total distance traveled is D km.

The average speed of the car can be calculated using the formula:

Average Speed = Total Distance / Total Time

1. The car traveled the first third of the distance at a speed of 40 km/h. 2. The car traveled the second third of the distance at a speed of 60 km/h. 3. The car traveled the last third of the distance at a speed of 120 km/h.

Since each third of the distance is equal, we can assume that each third is D/3 km.

The time taken for the first third of the distance is (D/3) / 40 hours.

The time taken for the second third of the distance is (D/3) / 60 hours.

The time taken for the last third of the distance is (D/3) / 120 hours.

Adding up these times will give us the total time taken.

The average speed is then calculated as:

Average Speed = Total Distance / Total Time

Let's calculate the average speed step by step:

1. Let's assume the total distance traveled is D km. 2. Each third of the distance is D/3 km. 3. The time taken for the first third of the distance is (D/3) / 40 hours. 4. The time taken for the second third of the distance is (D/3) / 60 hours. 5. The time taken for the last third of the distance is (D/3) / 120 hours. 6. The total time taken is **(D/3) / 40 + (D/3) / 60 + (D/3