Question

55 Баллов!!! После того, как школьник выпил всю воду из бутылки, в ней осталось V=0,8 мл воды в виде капель на стенках. Он плотно закрыл бутылку и поставил её около окна. Под действием солнечных лучей вся вода внутри бутылки испарилась. Определите плотность получившейся смеси, если первоначальная плотность воздуха составляет ρ0=1,2 кг/м3, а плотность воды — ρв=1000 кг/м3. Ответ выразите в кг/м3, округлив до десятых. Вместимость бутылки равна V0=2 л.

Answer 1

Плотность равна массе смеси, делённой на объём бутылки. p=M/V0;
Масса смеси равна сумме масс воздуха и воды. M=m1+m2;
Масса воздуха равна m1=p0*V0.
Масса воды равна m2=pв*Vв;
Получили окончательную формулу: p=(p0*V0+pв*Vв)/V0;
p=p0+pв*(Vв/V0);
p=1.2+1000*(0.05/500); здесь объём в миллилитрах.
p=1.2+0.1;
p=1.3 кг/м^3.
Так как используется не само значение объёмов, а их отношение, то переводить в м^3 не требуется, главное, чтобы объём был в одинаковых единицах, хоть в вёдрах, хоть в литрах.

Answer 2

Problem Analysis

In this problem, we are given that a student drinks all the water from a bottle, leaving behind 0.8 ml of water in the form of droplets on the bottle's walls. The student then tightly closes the bottle and places it near a window. The sunlight causes all the water inside the bottle to evaporate. We are asked to determine the density of the resulting mixture, given that the initial density of air is ρ0 = 1.2 kg/m^3 and the density of water is ρв = 1000 kg/m^3. The capacity of the bottle is V0 = 2 L.

Solution

To solve this problem, we need to consider the initial state of the bottle, when it contains only air, and the final state, when all the water has evaporated.

# Initial State:

The initial state of the bottle contains air and a small amount of water in the form of droplets on the walls. Since the student drinks all the water, we can assume that the water droplets are evenly distributed on the inner surface of the bottle. However, the volume of the droplets is given in milliliters (ml), while the densities are given in kilograms per cubic meter (kg/m^3). Therefore, we need to convert the volume of the droplets to cubic meters (m^3) to match the units.

Given: - Volume of water droplets, V = 0.8 ml = 0.8 × 10^(-6) m^3

Since the density of water is ρв = 1000 kg/m^3, we can calculate the mass of the water droplets using the formula:

mass = density × volume

mass = 1000 kg/m^3 × 0.8 × 10^(-6) m^3

Let's calculate the mass of the water droplets:

density_water = 1000  # kg/m^3
volume_droplets = 0.8 * 10**(-6)  # m^3

mass_droplets = density_water * volume_droplets
mass_droplets

The mass of the water droplets is approximately 0.0008 kg.

# Final State:

In the final state, all the water inside the bottle has evaporated, leaving behind only air. Since the bottle is tightly closed, the air inside the bottle remains at the same pressure as the surrounding air. Therefore, the density of the resulting mixture is the same as the density of air.

Given: - Initial density of air, ρ0 = 1.2 kg/m^3

The density of the resulting mixture is the same as the density of air:

density_mixture = 1.2  # kg/m^3

The density of the resulting mixture is 1.2 kg/m^3.

Answer

The density of the resulting mixture, after all the water has evaporated, is approximately 1.2 kg/m^3.