"Liquid Pressure" Pressure PPT courseware 3

Description

"Liquid Pressure" Pressure PPT courseware 3

learning target

1. Know what liquid pressure is and what causes liquid pressure.

2. Know the characteristics of the internal pressure of liquids

3. Learn to use the controlled variable method to study physical problems

A wooden block placed on a horizontal tabletop exerts 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 wall of the cup?

1. Characteristics of liquid pressure

Liquid has downward pressure

The liquid also exerts pressure on the side wall

Liquid pressure is related to depth

For the same liquid, the deeper the depth, the greater the pressure.

Summary: Laws of Liquid Pressure

The phenomenon shows that the liquid exerts pressure on the bottom of the container

Because the liquid is affected by gravity

The phenomenon shows that the liquid also exerts pressure on the side wall of the container

Because liquids are fluid

Pressure gauge principle

Principle of the pressure gauge: When the rubber membrane on the probe is subjected to pressure, a height difference appears between the liquid levels on both sides of the U-shaped tube. The height difference between the two sides represents the pressure. The greater the pressure, the greater the liquid level difference.

Experiment 1: Put the probe into a container of water to see if there is pressure inside the liquid.

Keep the depth of the probe in the water constant, change the direction of the probe and see if the pressure in the liquid at the same depth is equal in all directions.

Experiment 2: Change the depth of the pressure gauge probe in the water and see how the pressure of the liquid is related to the depth.

Phenomenon: The deeper the rubber membrane is placed in the water, the greater the height difference of the U-shaped tube.

Conclusion: From Figures A and B, we can see that the liquid pressure is related to ________; the more ______, the greater the pressure.

Experiment 3: Put the rubber membrane of the pressure gauge into water and salt water respectively. The height difference of the U-shaped tube of the pressure gauge is different.

Conclusion: At the same depth, the greater the density, the greater the liquid pressure.

2. The size of the liquid pressure

(1) Theoretical derivation:

Consider a liquid column with height h, density ρ, and cross-section S. but:

The volume of the liquid column V=sh.

The mass of the liquid column m=ρV=ρSh.

The weight of the liquid column G = mg = ρShg.

The pressure of the liquid column on the bottom surface F = G = ρShg.

The pressure of the liquid column on the bottom surface:

p=F/s=ρShg/S=ρgh

(2) Formulas and units:

Liquid pressure is related to liquid density and depth, and has nothing to do with liquid cross-sectional area.

(3) Note: How to understand depth

h in p=ρgh refers to the depth of the liquid, that is, the height from the liquid pressure level to the free liquid surface.

Distinguish between depth and height

Depth: The vertical distance from a point in a liquid to the free surface above.

Height: The vertical distance from a point in a liquid to the bottom of the container below.

What are the depth and height of point A?

1. As shown in the figure, tilt the test tube placed vertically. As the test tube tilts, the pressure of the liquid in the test tube on the bottom surface will be ( )

A.increase B.decrease

C. Unchanged D. Unable to determine

2. As shown in the figure, two identical test tubes are filled with different liquids of equal mass. Tube A is placed vertically, and tube B is placed at an angle. At this time, the liquid levels in the two tubes are at the same level, and the bottom of the tube is affected by the liquid. The pressure relationship is ( )

A. The pressure is the same B. The pressure at the bottom of the pipe is stronger

C.b The pressure at the bottom of the pipe is strong D.Unable to judge

1. What is the seawater pressure experienced by a diver who dives 50m below the sea surface? ρSeawater=1.03×103kg/m3

Solution: p=ρsea watergh

=1.03×103kg/m3×9.8N/kg×50m

=5.047×105Pa

Answer: The pressure exerted by seawater is 5.047×105Pa

2. The dam of a reservoir is 147m away from the bottom of the reservoir. When the water depth is 130m, what is the pressure of the water at the bottom of the dam?

Solution: p=ρwatergh

=103kg/m3×9.8N/kg×130m

=1.274×106Pa

Answer: The pressure of water at the bottom of the dam is 1.274×106Pa

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"Liquid Pressure" Pressure PPT courseware 2:

"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 into ______; ___..

"Liquid Pressure" Pressure PPT courseware:

"Liquid Pressure" Pressure PPT courseware I want to discuss Pascal's cracked bucket experiment. Pascal performed a famous experiment in 1648: He used a sealed bucket filled with water and inserted a slender tube into the lid of the bucket. Water is poured into thin pipes on the balcony of the building. Knot..

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Update Time: 2024-11-22

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