EntranceAccording to the law of communicating vessels. Pressure
Dependence of fluid pressure on depth
Fluid pressure increases with depth: at depth h fluid pressure р = ρgh , Where ρ - liquid density.
Vessels connected from below by a tube are called communicating vessels . In communicating vessels, the surfaces of a homogeneous liquid are set at the same level.
If communicating vessels are filled with liquids of different densities, then the heights of the columns of liquids above the level of their interface are determined by the relation: p 2 *h 2 = p 1 *h 1
Law of communicating vessels: in communicating vessels into which the same liquid is poured, the surface of the liquid is at the same level. If there are different liquids in communicating vessels, then the liquid level is higher in the vessel containing a liquid with a lower density.
Hydraulic Press
IN hydraulic press communicating vessels of different sections S2 And S1 filled with a homogeneous liquid, used to obtain a gain in strength - F2/F1, equal - S2/S1 .
Gateways
Locks are one or more chambers, each of which can accommodate several ships at the same time. The cells are separated from each other by tightly closing gates. In order for a ship to pass through a gate, the water levels on each side of the gate must be the same. To equalize the water levels, the gate is raised slightly, so that the sections of the sluice on opposite sides of the gate become communicating vessels.
This is a physical scalar quantity, which is determined by the formula
Atmosphere pressure
The atmosphere is the air envelope of the Earth, which is held by gravitational forces. The atmosphere has weight and puts pressure on all bodies on Earth. The atmospheric pressure is about 760 mmHg. or 1 atm., or 101325 Pa. Millimeter of mercury, atmosphere are various non-system units of pressure measurement. Atmospheric pressure decreases by 1 mmHg. when rising above the Earth every 11m.
What is a pressure of 1 atm? A strong man's handshake is 0.1 atm, a boxer's punch is several atmospheric units. The pressure of a stiletto heel is 100 atmospheres. If you put a 100 kg weight on your palm, you will get an uneven pressure of one atmosphere; if you dive 10 m under water, you will get a uniform pressure of 1 atmosphere. The uniform pressure is easily tolerated by the human body. Normal atmospheric pressure, which affects every person, is compensated by internal pressure, so we do not notice it at all, despite the fact that it is quite significant.
Pascal's law
Pressure on a liquid or gas is transmitted equally in all directions.
Pressure inside a liquid (gas) at the same depth equally in all directions (left to right, down and up!)
Hydrostatic pressure
This is the pressure of a liquid column at the bottom of the vessel. What force creates pressure? The liquid has a weight that presses on the bottom.
Liquid pressure at the bottom
The pressure at the bottom of the vessel does not depend on the shape of the vessel, but depends on the area of its bottom. In this case, the pressure force on the bottom can be greater or less than the force of gravity of the liquid in the vessel. This is "hydrostatic paradox".
The hydrostatic pressure on the wall of the vessel is distributed unevenly: at the surface of the liquid it is zero (without taking into account atmospheric pressure), inside the liquid it changes in direct proportion to the depth and reaches a value at the bottom level. This variable pressure can be replaced by medium pressure
Communicating vessels
These are vessels that have a common channel below.
A homogeneous liquid is established in communicating vessels at the same level, regardless of the shape of the vessels, as can be seen in the photograph.
Dissimilar liquids are installed in communicating vessels according to the formula
Hydraulic Press
A hydraulic press consists of two communicating cylindrical vessels. Pistons with areas S 1 and S 2 move in the vessels. The cylinders are filled with technical oil.
The volume of liquid displaced by the small piston enters the large cylinder.
A hydraulic press gives a gain in force as many times as the area of the larger piston is greater than the area of the smaller one. A hydraulic press does not provide any benefit in work.
In practice, due to the presence of friction:
If the force is directed at an angle to the normal (perpendicular), then the pressure is determined by the formula
Gases and liquids under pressure are widely used in industrial technology. For example, a pneumatic jackhammer. Doors on buses and subways, brakes on trains and trucks are also operated using compressed air.
There are also mechanisms that operate using compressed fluid. They are called hydraulic. For example, a hydraulic press device.
The numerical value of atmospheric pressure was determined experimentally in 1643 by the Italian scientist E. Torricelli.
A glass tube about a meter long, sealed at one end, is filled to the top with mercury. Then, tightly closing the hole with your finger, the tube is turned over and lowered into a bowl of mercury, after which the finger is removed. The mercury begins to pour out of the tube, but not all of it: what remains is a “column” 76 cm high, counting from the level in the bowl. It is noteworthy that this height does not depend either on the length of the tube or on the depth of its immersion.
Atmospheric pressure balances the hydrostatic pressure of the mercury column. According to Pascal's law, atmospheric pressure pushes upward on the mercury column. And the column of mercury presses down with its weight. Mercury stops falling when these pressures are the same. By calculating the hydrostatic pressure of mercury at a known altitude, we determined the atmospheric pressure.
The Torricelli tube with ruler is the simplest barometer– a device for measuring atmospheric pressure
They are also used to measure atmospheric pressure. aneroid barometer.
Since atmospheric pressure decreases with distance from the Earth's surface, the aneroid scale can be graduated in meters. In this case it is called altimeter.
Let a rectangular metal bar with base area S and height h lie at the bottom of a vessel into which water is poured to a height H, H>h. How to determine the force of pressure of a block on the bottom of a vessel?
There are two possible cases! Let the block fit loosely to the bottom of the vessel, then the fluid pressure force acts on the block from below. This force is greater than the force of fluid pressure from above, so the Archimedes force arises. The Archimedes force is the result of the difference in the force of hydrostatic pressure on the lower face of the block and the upper face, depending on the height of the block and the area of the base. 
We use Newton's 2nd law:
Let's consider the second possible case. Let the block fit so tightly to the bottom that liquid does not leak under it. There is no fluid pressure from below, therefore the Archimedes force is zero. From above, the pressure force of the liquid and the atmosphere acts on the block. 
We use Newton's 2nd law for this case:
p 0 - atmospheric pressure,
p is the hydrostatic pressure of a liquid column of height H-h.
Alimkhanova Seule Ibraevna
Physics teacher at KSU "Gerasimovskaya Secondary School" in the village of Gerasimovka, Ulan district of the East Kazakhstan region, higher education.
Short-term integrated lesson planning
Physics and Geography
Topic: “Communicating vessels. Communicating vessels in nature"
Class: ____7 B /Russian language of instruction/ _________
Physics teacher:__Alimkhanova Seule Ibraevna _________
Geography teacher:__Chotieva Ainur Mukhametsharifovna ________
Planning table
Lesson 3Title of the lesson:
Communicating vessels
Textbook "Physics" for 7th grade,
lesson notes, presentation inPowerPoint, demonstration material for the experiment, samples of vessels
Common goals
Ensure effective assimilation of this material, the ability to distinguish between types of communicating vessels. Deepen knowledge of the topic in integration with geography, forming common views about the universe. Continue the formation of natural and mathematical literacy, developing functional literacy.
Learning outcome
Come to the conclusion that communicating vessels not only exist in physics, but also in nature. They distinguish between types of communicating vessels and are able to find convergence in everyday life, in practice and in nature. They know the concepts.
Key Ideas
The scientific discovery of the properties of communicating vessels dates back to1586 (Dutch scientist Stevin ). But it was known to the priests of ancient Greece. Archaeologists have discovered a water supply system in Georgia (13th century), working on the principle of communicating vessels. We encounter communicating vessels every day. Give examples of them? We use these vessels for brewing tea, boiling water and watering flowers in the garden. Guys, have you guessed which vessels we are talking about? ( Watering can, teapot, coffee pot...). Water poured, for example, into a kettle, always stands at the same level in the kettle reservoir and in the side tube. The side tube and the reservoir are connected to each other at the bottom. Guys, what kind of vessels do you think we will call communicating?Communicating vessels are vessels connected to each other at the bottom.
All the seas and oceans of the world are also communicating vessels. After all, they are all connected by straits. Therefore, sea levels are the same throughout the world.
An aqueduct is a water channel supported by bridges. Aqueducts were used in ancient times as ground-based prototypes of modern water supply systems.
Ancient Roman engineers were good at solving complex technical problems, but they were not familiar enough with the basics of physics. The Roman water supply system was laid above ground, but wouldn’t it have been easier to do it the way it is now, by laying pipes underground.
Fountain.
The fountain's action is also based on the principle of communicating vessels. Water from the reservoir flows through the tube and tends to rise to the same level as in the large vessel. But the tube ends, and the water shoots upward in a fountain. Even if you position the hose so that its slope rises, water does not cease to flow from the fountain.
Modern plumbing.
You see almost the same fountain every day when you open the tap, because the operation of the water supply is based on the same principle.
An example of communicating vessels is an artesian well.
Gateway.
The lock is used to transfer ships from one level of the river to another. The sluice device is also based on the principle of communicating vessels.
People use the law of communicating vessels in various technical devices: water pipelines with a water tower; water measuring glasses; hydraulic press; fountains; locks; siphons under the sink, “water seals” in the sewer system.
People use the law of communicating vessels in everyday life (teapot, coffee pot, watering can).
In the water measuring glass of a steam boiler, the steam boiler (1) and the water measuring glass (3) are communicating vessels.
Tasks
1. Updating knowledge - demonstrating vessels and finding differences, drawing conclusions
2. Division into groups
3. Practical work in small groups - Definition of the Law of Communicating Vessels:
I group: Experience No. 1
Pour water into one of the tubes (SS).
Answer the questions: (we do not remove the clamp)
a) What happens if you remove the clamp?
b) How will the water then be distributed through the glass tubes?
Test your assumptions, hypotheses, answers) experimentally.
How will the liquid behave if one of the tubes:
Raise
Lower
Tilt in different directions?
Writing in a notebook
Laws (SS)
I part of the law (SS): Homogeneous liquid in CC leave 7 cm is installed at the same level.
II group: Experience No. 2
Describe the device on your desk:
What is the shape of the tubes?
( different, the samenarrower, wider )
Base (aboutgeneral or miscellaneous)
What can you call this device?
How many SS are there on the device?
5.Pour water into the CC
What will happen to the liquid level in the tubes?
Homogeneous liquid in CC any shape
installed at the same level.
III group: Experience No. 3
In (SS) we pour different liquids: water and sunflower oil, of equal volume.
What do you see?
a) The levels will be different.
b) Liquids do not mix
c) Where do you see this from? Show me where they don't mix
Let's call this place the interface between two liquids.Let's draw a horizontal line through this border.
Working with a drawing
What do you see in the slide picture and in the picture in front of you? those. above this line.
a) Two pillars: a pillar of water and a pillar of oil.
b) What is the difference between a column of water and a column of oil: height
V)Oil column height moreheight of the water column.
So you brought it outII part of the law (SS).
Here one more physical quantity is missing.
What size did you forget?
a) How else do water and oil differ from each other: density.
b) What is their density?
Water density 1000 kg/m, oil density 930 kg/m
a) Height of oil column with lower densitymore , the height of the water column with higher density.
d) But instead of oil and water there may be another liquid: for example: mercury, alcohol, glycerin. That's whyII part of the law (SS) should be given in general form for all liquids.
b) the height of the liquid columns will depend on its density
c) the lower the density of the liquid, the higher its column in the vessel.
II part of the law (SS):
In (SS) containing different liquids, the height of the liquid column with a lower density will be greater than the height of the liquid column with a higher density
4. Working with a drawing - compare.
5. Relaxation – Eye exercise according to the map
6. Division into small groups
7. Work in small groups - creating a poster
1 group – Artesian wells
2nd group – Geysers
Group 3 – Water pipeline
Speakers from each group
8. Demonstration experience “Do-it-yourself fountain”
9. Reflection – showing a video aboutccommunicating sos
10. Homework
11. Assessment
Additional tasks
1. Create a dialogue
2. Working with the map
3. Practical skills
4. Working with advanced tasks
Further Reading
Textbook “Continents and Oceans” for grade 7, §48, reader for the textbook
Textbook Geography" for 6th grade
| Number groups | Collaboration in a group (distribution and fulfillment of responsibilities) | Behavior (not interfering with work other groups, not take your mind off complete the task, do not shout) | Disclosure material, tasks, Topics | Listening skills presentations other groups, ask questions, make additions | General point |
Branch of the Municipal Educational Institution "Tondoshenskaya School" "Verkh-Biyskaya School"
634 " style="width:475.35pt"> What law is manifested in this experience? Why does water leak out of the holes? What does it mean that water pressure increases with depth? Three vessels with the same bottom area are filled with water to the same level. Which vessel contains more water? Is the water pressure at the bottom the same in these vessels? Does the water press with equal force on the bottom of these vessels? There is air above the liquid on the left side of the container. What height of the liquid column should be taken into account when calculating the pressure at the bottom of the vessel: H or H1?
Teacher:
Water flows into one vessel,
But that’s really not a problem,
Since they are neighbors, after all,
And others have the same amount of water.
What are they called?
What do you know about them, tell me?
Where are they used?
3.The stage of acquiring new knowledge.
In front of you on the table is a teapot, a watering can, and vessels of various shapes. (Appendix 2)
What do you think these vessels have in common?
What are these vessels called?
Students draw a conclusion. Vessels connected to each other below the liquid level are called communicating.
Today in class we will talk about communicating vessels.
Please write down the topic of the lesson. Students write down the topic of the lesson in their notes. (Appendix 3)
Let's formulate the goals of the lesson together.
Listen to students' opinions.
1. Form a concept about communicating vessels and their properties, find out how the surfaces of homogeneous and inhomogeneous liquid will be located in communicating vessels.
2. Show the widespread use of communicating vessels in everyday life, technology, and nature.
3. Be able to apply the acquired knowledge to solve questions and problems.
Let's conduct an experiment with communicating vessels. Let's take two glass tubes connected by a rubber tube. We will clamp the rubber tube in the middle. Pour water into each leg of the vessel. (Demonstration of experience)
Will liquid flow from one container to another if the clamp is opened? Why? (Listen to answers)
Let's check. (Open the clamp)
You see the liquid began to flow. Why?
How will the liquid behave if one of the tubes is lifted?
The liquid will settle in both vessels at the same level.
How will the liquid behave if one of the tubes is lowered?
The liquid will settle in both vessels at the same level.
What can be said about the fluid levels in both legs of communicating vessels if there is no fluid movement in it?
In a liquid at rest the levels will be the same.
Let's formulate a conclusion:
In communicating vessels, the free surface of the liquid at rest is at the same level. Mark the fluid level in the first picture in your notes. (Appendix 3)
Is it possible to theoretically prove this?
We know that at the same level, according to Pascal’s law, the pressure at all points of the liquid is the same, i.e. р1=р2..gif" width="9 height=14" height="14">gh2. We equate them gh1 =gh2 Let's reduce the common factors g and get h1=h2, which is what we needed to prove.
Record the conclusion. Students write down their conclusions in notes. (Appendix 3)
Does the position of the liquid level in communicating vessels depend on the width of the vessel? Let's test this experimentally. To do this, pour water into these vessels. (Experiment with vessels of different widths.)
What conclusion can be drawn?
Based on experience, students conclude: in vessels of any width, a homogeneous liquid is established at the same level.
Make appropriate notes on the second picture. Students mark the liquid level in the second picture. (Appendix 3)
Does the position of the liquid level in communicating vessels depend on the shape of the vessel?
Students continue to work with vessels of different shapes. (Experience with vessels of different shapes)
What conclusion can you draw? Based on experience, students conclude: in vessels of any shape, a homogeneous liquid is established at the same level.
Make the appropriate designation in the third picture. Students mark the liquid level in the third picture. (Appendix 3)
And if we pour two immiscible liquids of different densities into communicating vessels. Will they be located on the same level? One vessel is filled with water, the other with oil.
What conclusion can you draw: the heights of columns of dissimilar liquids in communicating vessels are different. Why?
The heights of columns of dissimilar liquids in communicating vessels are inversely proportional to their densities. According to Pascal's law p1=p2. Pressure p1=1gh1 and p2=2gh2. Hence 1gh1=2gh2
i.e. h1: h2=2:1
Record this conclusion. (Appendix 3)
Now, try to identify an unknown substance poured into a communicating vessel, if you know that there is water in the left knee. Do not forget that the task must be formalized in a supporting outline. (On the table there is a ruler, a table of densities, vessels with different liquids) What kind of substance is poured in your communicating vessels? At the end of the work, students give an answer to the question what kind of substance is poured into their communicating vessels. (Appendix3)
Now listen to the reports on the practical use of communicating vessels.
1. Properties of communicating vessels. (Appendix 4)
2. Artesian well. (Appendix 4, slide 1)
3. Natural communicating vessel. (Appendix 4, slide 2)
4. Gateways. (Appendix 4, slide 3)
Thanks guys. Your posts were interesting.
4. The stage of consolidating new knowledge.
You must write in the answer table the letters corresponding to the correct answer to each question. Students work on tests. (Appendix 5)
What code word did you get? That's right, “Pascal”. Perform the test for "3", "4" or "5".
And before I say thank you and goodbye to everyone, I ask you to evaluate your work in class. Reflection. Place colored circles on the “Ladder of Knowledge”
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5.Homework. §39 Think about how you can build a fountain, draw a diagram of such a device and explain its operation.
Application
Application
Application
Topic: “__________________________________________ vessels”
Vessels______________________________________________________________________________________________________________________________ are called __________________
A) ρ=13600 kg/m3 – mercury; B) ρ=1000 kg/m3 – water; B) ρ=930 kg/m3 vegetable oil
Application
Application of communicating vessels
1. The properties of communicating vessels, in which water tends to occupy a position with the same level in different parts of the vessel, have been used by humans since ancient times. Every day we take advantage of the fact that the water in the kettle and its spout is at the same horizontal level. When the kettle is slowly tilted, this level does not change, as a result, water begins to pour out of the spout.
https://pandia.ru/text/80/296/images/image018_17.gif" align="left" width="221" height="105 src=">
Modern electric kettles do not have a long spout, but often have a water level indicator, which is also an elbow of a communicating vessel in which a bright indicator floats on the surface.
2. Artesian well.
The action of an artesian well is based on the principle of communicating vessels. The location of the well is chosen at the lowest point of the landscape through which groundwater flows. According to the principle of communicating vessels, water begins to rise through the well. (Slide 1)
3. Natural communicating vessel
On continents there are areas located below sea level. The seas and the lowlands of the land located at the same level with them form communicating vessels. The water tries to equalize the levels in the two vessels, which is why areas below sea level are very wet. The Dead Sea is the lowest landmass (392 m below sea level). (Slide 2)
Reservoir" href="/text/category/vodoem/" rel="bookmark">reservoirs with different water levels.
Locks allow a ship to move from one body of water to another, lying above or below the level of the first body of water. Shipping canals using locks connected the inland waters of the European part of Russia with the seas: Cheboksary Gateway, Sheksninsky Gateway and etc.
By gateway Panama Canal ships can pass in both directions at the same time. There are 2 cascades of locks on the Panama Canal. (Slide 3)
Application
Which vessels are communicating? |
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Which coffee pot can hold more coffee? |
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Will liquid flow from one container to another if you open the tap? |
R - not always. |
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Which knee has fresh water and which has salt water? | L – salty on the left, fresh on the right; K – fresh on the left, salty on the right. |
|
In which of the communicating vessels is the liquid level shown incorrectly? | ||
What mark corresponds to the liquid level in the left vessel? | ||
Which picture shows communicating vessels? |
Keyword:
to "3".
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2). In which bend of the tube is it located? less dense liquid?
A) in the right B) in the left
C) the density of the liquids is the same.
3).
(pages 95-96 of the textbook)
to "4".
Two vessels are connected by a rubber tube with a tap
and filled with liquid. The left vessel is kerosene, the right is water.
1). In which vessel is the pressure on the tap greater?
A) in the left B) in the right C) the same.
2). Will liquid overflow if you open the tap?
· A) A) will be from the left vessel to the right.
B) will be from the right vessel to the left.
B) there won't be.
3). Give examples of communicating vessels in everyday life and technology.
to "5".
7th grade" href="/text/category/7_klass/" rel="bookmark">7th grade" publishing house "Drofa", 2011.
2. Internet resources
Images -images. yandex. ru