Physics questions in junior high school infusion bottles and outside the bottle

Your teacher is right.

The pressure of the air in the bottle is equal to the atmospheric pressure.

What you said:"Personally, I think it is the same, because in this process, the volume of the liquid decreases, the volume inside the bottle increases, the pressure decreases, and the gas outside the bottle is replenished. "That's right. But"Keep the pressure constant"is wrong. Cause:

P gas + liquid GH = P0

H is getting smaller, and apparently P gas is increasing.

This problem cannot be solved with a certain quality of gas, because the gas in the bottle is not of a fixed mass, but more and more.

It's a bit of a mess upstairs, but I'm going to give you a simple explanation, and you think, if you fill a bottle with water and pour it out, you can keep the bottle in a vacuum. The infusion bottle is the same principle, when the liquid flows out, the air pressure in the bottle will decrease, if the liquid flows out completely, without considering the air inflow, then the bottle is a vacuum. At the same time, if air enters, then it is not a vacuum in the bottle that will generate pressure, and at this time, this part of the air + the liquid flowing out = all the original volume of the whole bottle.

Of course, the pressure increases.

Infusion bottles (hard-shelled plastic bottles or glass bottles), the air inside the bottle is communicated with the outside of the bottle, and when the liquid in the bottle is reduced, the air outside the bottle is replenished to the bottle in time to keep the air pressure in the bottle unchanged. (The liquid decreases, the space increases, the pressure decreases, the pressure outside the bottle is stronger than the pressure inside the bottle, and the air is continuously pressed into the bottle from the outside of the bottle, so as to keep the pressure unchanged.) The volume of a gas of a certain mass is inversely proportional to the pressure at a certain temperature, and the larger the volume, the smaller the pressure).

The pressure inside the bottle is inconvenient and is always atmospheric.

Why is it balance and is it equal to keep balance, or is it equal to keep balance, your teacher really misunderstands people by reversing cause and effect, and people who are capable please help me solve the problem.

The pressure of the liquid medicine is increased. In fact, raising the hanging bottle is to increase the pressure difference between the liquid medicine and the blood in the hanging bottle. As a result, the pressure of the "inflow into the patient's blood vessels" is increased. Because, the pressure flowing into the patient's vascular solution = liquid medicine *g*h

Liquid medicine - density of liquid medicine, g gravitational acceleration, height of h hanging bottle).

The function of tube B is to introduce air into the medicine bottle, in fact, it is also to increase the pressure of the liquid medicine in the hanging bottle (because the unfilled part of the bottle is vacuumed when the liquid is bottled); This is also the reason why the liquid medicine does not flow out of the B tube, that is, the pressure inside the bottle is less than the atmospheric pressure.

Pressure: Communicates with the atmosphere to maintain a certain air pressure inside the bottle. [It also ensures that with the decrease of the height of the liquid medicine in the bottle, the pressure of the liquid medicine on the patient's blood vessels remains unchanged and the flow rate remains unchanged].

a. Oxygen, air, and nitrogen are all insoluble in water and cannot be identified, so the option is wrong B. Nitrogen, oxygen and air have no color, and they cannot be identified by the square ridge cavity dust method of observing the color, so the option is wrong

c. Carbon dioxide can make the clarified lime water turbid, and the use of clarified lime water cannot distinguish nitrogen, oxygen and air, so the choice is wrong

d. Insert a wooden strip burning with cherry blossoms, if the wooden strip burns more vigorously, it is oxygen; If the wood burns normally, it is air; If the wood is extinguished, it is nitrogen; The phenomenon is obvious, and these three gases can be identified at one time, so the choice is correct

Therefore, d