"Pressure inside Liquids" Pressure and Buoyancy PPT Courseware 2

Description

"Pressure inside Liquids" Pressure and Buoyancy PPT Courseware 2

teaching objectives

1. Know the causes and measurement methods of liquid pressure

2. Understand the rules of internal pressure of liquids

3. Know how to calculate the pressure of a liquid

Similar to the way a solid exerts pressure on a supporting surface due to the action of gravity, a liquid also generates pressure due to its fluidity and the action of gravity. What are the characteristics of liquid pressure?

Does the liquid exert pressure on the bottom of the container?

Does the liquid exert pressure on the side walls of the container?

Summarize the rules from experimental phenomena:

(1) The phenomenon shows that the liquid has pressure on the bottom of the container because the liquid is affected by gravity.

(2) The phenomenon shows that the liquid exerts pressure on the side wall of the container because the liquid is fluid.

The law of liquid pressure:

1. _____ ("existence" or "absence") pressure in all directions inside the liquid.

2. At the same depth, the pressure of liquid in all directions ______.

3. The pressure of a liquid ______ as the depth increases;

4. The pressure of a liquid also depends on the density of the liquid ______.

think about it

Why do divers use different wetsuits in different depths of water?

The deeper the water, the greater the pressure generated

When building a dam, the lower part of the dam is always wider than the upper part to withstand the water pressure. Why?

The deeper the water, the greater the pressure generated

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 under 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. How heavy is this liquid column? The pressure on the plane is:

F=G=mg=ρgsh

4. The pressure on the plane P=F/S=ρgh

Liquid pressure calculation formula: p=ρgh

Notice

Liquid pressure is only related to the density and depth of the liquid, and has nothing to do with the gravity, volume, shape, etc. of the liquid.

This formula only applies to the pressure of liquids and cylinders on the horizontal surface, while P=F/S is the definition of pressure and is applicable to all pressure calculations.

Class exercises

1. Regarding liquid pressure, which of the following statements is correct ( )

A. The pressure of a liquid is caused by the gravity of the liquid, so the pressure direction inside the liquid is always downward.

B. At the same depth of the liquid, the downward pressure of the liquid is stronger than the upward pressure.

C. At the same depth of the liquid, the pressure of different liquids is generally different

D. All objects or surfaces in contact with liquid are subject to the pressure of the liquid

2. As shown in the figure, two containers A and B contain the same liquid. Which container has a greater liquid pressure at the bottom ( )

A.A B.B

C. Same size D. Unable to judge

3. As shown in the figure, two tubes contain the same liquid, and the pressure at the bottom of the two test tubes is compared ( )

A. University A B. University B

C. Same size D. Incomparable

Summary of this lesson

1.p=ρgh is derived from p=F/S, p=F/S is applicable to any situation,

The key is to find the corresponding pressure on the stressed area.

p=ρgh is only suitable for finding the pressure of liquids.

2. The h in the formula p=ρgh refers to the vertical depth from somewhere in the liquid to the free surface of the liquid.

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"Pressure inside Liquids" Pressure and Buoyancy PPT Courseware 3:

"Pressure inside the liquid" Pressure and buoyancy PPT courseware 3 Key points Characteristics of the internal pressure of the liquid The determinants of the strength of the liquid pressure The rules of the internal pressure of the liquid and the rules for calculating the internal pressure of the liquid There is pressure inside the liquid, and the same type of liquid is at the same depth in all directions. .

"Pressure inside Liquids" Pressure and Buoyancy PPT Courseware:

"Pressure inside Liquids" Pressure and Buoyancy PPT Courseware Observation and Thinking As shown in the picture, a wooden block placed on a horizontal tabletop will exert pressure on the tabletop, so will the water in the cup exert pressure on the bottom of the cup? Will the water exert pressure on the side walls of the cup? Think about it...

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Update Time: 2024-06-29

This template belongs to Physics courseware Beijing Normal University eighth grade physics volume 2 industry PPT template

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