Question

8«Б» класс пришёл на урок физкультуры в школьный бассейн в полном составе. Рассчитай массовую долю учеников в бассейне, если в классе 25 учащихся, средняя масса тела восьмиклассника составляет 48 кг. Бассейн представляет собой параллелепипед, длина которого равна 25 м, ширин. — 8 м, глубина — 2 м. Плотность воды в бассейне считай равной 1000 гл.​

Answer 1

Ответ:

0,00299103 от 1 или 0,299103%

Объяяясненииииииииие ее:

м3=1000л=1000кг

масса воды в бассейне = 25*8*2*1000=400 000

масса школьников = 25*48=1200
общая масса так называемой смеси школьников с водой 401 200

отсюда если 401 200 это 1 или же 100%

по пропорции вычисляем какая часть будет 1 200:

1200/х=401200/1
х=1200/401200=0,00299103

если нужны проценты, домножаем на 100% = 0,299103%

Answer 2

Calculation of the Mass Fraction of Students in the Pool

To calculate the mass fraction of students in the pool, we need to determine the total mass of the students and the total mass of the water in the pool.

Given information: - Number of students in the class: 25 - Average mass of an eighth-grader: 48 kg - Dimensions of the pool: length = 25 m, width = 8 m, depth = 2 m - Density of water in the pool: 1000 g/L

First, let's calculate the total mass of the students in the class: Total mass of students = Number of students × Average mass of an eighth-grader.

Total mass of students = 25 students × 48 kg/student.

To calculate the total mass of the students, we multiply the number of students by the average mass of an eighth-grader.

Next, let's calculate the volume of the pool: Volume of the pool = Length × Width × Depth.

Volume of the pool = 25 m × 8 m × 2 m.

To calculate the volume of the pool, we multiply the length, width, and depth of the pool.

Now, let's calculate the mass of the water in the pool: Mass of water in the pool = Volume of the pool × Density of water.

Mass of water in the pool = (25 m × 8 m × 2 m) × 1000 g/L.

To calculate the mass of the water in the pool, we multiply the volume of the pool by the density of water.

Finally, let's calculate the mass fraction of the students in the pool: Mass fraction of students = Total mass of students / (Total mass of students + Mass of water in the pool).

Mass fraction of students = Total mass of students / (Total mass of students + (25 m × 8 m × 2 m) × 1000 g/L).

By dividing the total mass of the students by the sum of the total mass of the students and the mass of water in the pool, we can calculate the mass fraction of the students.

Please note that the density of water is assumed to be 1000 g/L.

Let's perform the calculations:

Total mass of students = 25 students × 48 kg/student = 1200 kg.

Volume of the pool = 25 m × 8 m × 2 m = 400 m³.

Mass of water in the pool = (25 m × 8 m × 2 m) × 1000 g/L = 8000000 g.

Mass fraction of students = 1200 kg / (1200 kg + 8000000 g) = 0.00015.

Therefore, the mass fraction of the students in the pool is approximately 0.00015.

Please note that the calculations assume that the students are fully submerged in the water and that the average mass of an eighth-grader is constant for all students in the class.