"Liquid Pressure" Pressure PPT Courseware 2

Description

"Liquid Pressure" Pressure PPT Courseware 2

Preparation before class

1. In order to compare the effect of pressure, the physical quantity pressure is introduced in physics. The pressure formula: ____

2.The relationship between gravity and mass: ______

3. Density formula: _____, deformed to ______; ______

learning target

1. Know the causes of liquid pressure

2. Know the characteristics of the internal pressure of liquids

3. Know what factors determine the size of liquid pressure and the derivation and application of the liquid pressure formula

Why does a liquid exert pressure on the bottom of a container?

Because the liquid is subject to gravity

Why does a liquid exert pressure on the walls of a container?

Because liquids are fluid

The cause of liquid pressure: liquid is affected by gravity and has fluidity

Function: An instrument that measures the internal pressure of liquids

Structure: U-shaped tube (containing the same liquid), metal box (covered with rubber film), connected with rubber tubes

Principle: No pressure is applied to the rubber membrane, and the liquid levels on both sides of the U-shaped tube are equal.

Add pressure to the rubber membrane, and the pressure is transmitted to the liquid surface through the air. The liquid level drops while the liquid level on the other side rises. The liquid levels on both sides of the U-shaped tube form a height difference. The greater the pressure, the greater the height difference.

Hydraulic features:

1. There is pressure inside the liquid in all directions;

At the same depth, the pressure of the liquid is equal in all directions;

2. Liquid pressure is also related to the depth of the liquid: as the depth increases, the pressure of the liquid increases.

3. Liquid pressure is related to liquid density:

At the same depth, the greater the density of the liquid, the greater the pressure.

How to calculate the pressure inside a liquid

Idea:

Imagine that there is a liquid column with a depth h and a cross-sectional area s below the liquid surface. Calculate the pressure generated by this section of liquid column, and you can get the pressure formula at the depth h inside the liquid.

Formula derivation steps:

1.The volume of this liquid column: V=sh

2.The mass of this liquid column: m=ρv=ρSh

3. The pressure of this liquid column on the horizontal surface is: F=G=mg=ρgsh

4. Pressure on the horizontal plane

P=F/S=ρgh

In the liquid pressure calculation formula p =ρgh:

(1) p is the pressure h deep inside the liquid, the unit is pa;

(2) ρ is the density of the liquid, the unit is kg/m3;

(3) h is depth, which refers to the distance from the research point to the liquid surface. The unit is m.

It can be seen from the hydraulic formula that the pressure at a certain depth inside the liquid is only related to the _______ of the liquid and the ______ of the liquid; it has nothing to do with the force-bearing area, mass, gravity, volume and other factors.

Learning detection

1. Compare the pressures at points a and b in the following figures.

2. There is a certain amount of water in the test tube as shown in the figure. When the test tube is placed vertically, the pressure of the water on the bottom of the tube is p1; when the tube is placed tilted, the pressure of the water on the bottom of the tube is p2. Compare p1 and p2. size, then ( )

A. p1>p2B． p1

C. p1=p2D． Insufficient conditions to judge

3. As shown in the figure, different containers A and B contain salt water and water with the same depth respectively. The relationship between the pressure of the liquid on the bottom of the container is: PA____PB (fill in ">", "<", "=").

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For more information about the "Pressure, Liquid Pressure" PPT courseware, please click on the "Pressure ppt Liquid Pressure ppt" tab.

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Update Time: 2024-10-02

This template belongs to Physics courseware Lu Jiao Edition Eighth Grade Physics Volume 2 industry PPT template

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