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PRESSURE

1. Pressure on solid2. Pressure on liquid

3. Pressure on gases

Standard

Competence

Basic

Competence

Learning

Objective

Learning

Material

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STANDARD OF COMPETENCE

Comprehending

work, force, and

energy role in dailylife.

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BASIC COMPETENCE

To search the

Pressure on solid,

liquid and gas thing

and its application in

life

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LEARNING OBJECTIVES

1. To get a concept about air pressure.

2. To calculate the air pressure in close chamber using open-

tube manometer.

3. To understand about Boyles Law.

4. To solve simple problem about Boyless Law.

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PRESSURE ON GASES

1. Air pressure/Atmosphericpressure

2. Measuring Instrument of

Air Pressure.3. Boyles Law

http://www.youtube.com/watch?v=WSjMlBLp_fI

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When you take off or land in an aircraft, your ears may hurt

or feel uncomfortable. This is because your eardrums can

feel changes in air pressure as the aircraft moves quickly up

and down.

But what is air pressure?

Can you feel air pressure?

Atmospheric Pressure/ Air Pressure

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What is Air Pressure?

It is caused by the weight of all the air in the

atmosphere pressing down on Earth.

It is also known as atmospheric pressure.

Air pressure changes with the height and also

when air warms up or cools down.

Changes in air pressure cause changes in the

weather.

Atmospheric Pressure/ Air Pressure

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Air pressure is

equal in all

directions.

Atmospheric Pressure/ Air Pressure

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Atmospheric Pressure/ Air Pressure

Changing weather conditions

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Atmospheric Pressure/ Air Pressure

Changing altitude

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Measuring Instrument of Air Pressure.

Barometer> device that

measures atmospheric

pressure

Invented by Evangelista

Torricelli in 1643

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Measuring Instrument of Air Pressure.

A manometer measures the

pressure of a gas in a

container

Gas pressure is the force

exerted by the collisions of

gas particles with a surface

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Working Principle of Open-tube Manometer.

If the gas pressure less than

atmospheric pressure, the

level of mercury in the columnconnected to the enclosed

space will be higher than the

level of mercury in the other

column.

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Working Principle of Open-tube Manometer.

We can formulated that :

columnbothinsurfacemercury

oflevelofdifference-pressurecatmospheri=Pgas

h0gas P=P

Where Po = 76 cmHg

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Working Principle of Open-tube Manometer.

If the gas pressure greater than

atmospheric pressure, the level

of mercury in the column

connected to the enclosed

space will be lower than the

level of mercury in the other

column.

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Working Principle of Open-tube Manometer.

We can formulated that :

columnbothinsurfacemercury

oflevelofdifferencepressurecatmospheri=Pgas

h0gas P=P

Where Po = 76 cmHg

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Boyles Law

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Boyles Law

From the picture before we can conclude that

Boyle state :

At constant temperature, gas pressure in

closed comber is inversely proportional

with its volume.

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Boyles Law

We can formulated as :

CPV

2211 VPVP

Where :

P= pressure (Pa)

)3(mvolumev

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