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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 OBJECTIVES1. To find relation between force , pressure and length

of area with force through experiment.

2. To apply the connecting receptacle in life

3. To describe the Pascals Law and Archimedes law

by simple experiment, also the Application life.

4. To show several technology product in life

connected with the concept of floating,flying,

Sinking thing.

5. To go around to find the pressure concept

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PRESSURE ON SOLID

Lets see the picture and question above:

why our foot will fell pain when we use high

hells than flat shoes? why chicken difficult to walk in mud than a

duck?

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Which is more painful ?

sick !!!

No sick !!!

Why ??

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30 N60 N

A

B

( I ) ( II )

Which is deeper ?

( I ) ( II )

sand

sand

60 N

60 N

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The more of the force,

the more of pressure.

Pressure force

60 N

A30 N

B

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Pressure wide of contact surface

30 N

The more of the wide contact surface,the smaller the pressure.

30 NA B

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So.. What is pressure?

We can conclude that :

Pressure is the amountof force in a unit of wide.

based on these explanation, the amount of

pressure is influenced by :

1. Force ( F )

2. The wide of area contact (A)( A )

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A

FPPressure

Where

P = pressure (1 N/m2 = 1 Pa)

F = force (N)

A = area surface(m2)

We can formulated pressure as :

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Example

A B

There are two women that have the same

weight, that is 60N. The first woman uses a

high heel shoes but this one is flat shoes.

Which has bigger pressure ?

If the wide of shoes surface of A is 40 cm

and B is 100 cm . How much is the

pressure of each woman to the floor ?

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Solution

A. Known : F = 60 NA = 40 cm

= 4.10-3mQuestion P = ?

Answer : FP = ---

---A60 N

= ------------

B. Known : F = 60 N

A = 100 cm

= 1.10-2 m

Question P = ?

Answer : F

P = ------

A

60 N

= ------------1.10-2 m

= 6000 N/m

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The application of pressure on solid :

-> A pointed nails has bigger pressure

than the others.

-> A sharp knife has bigger pressure.

-> The pressure of the truck container

cause the road is damaged.

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Exercise

An elephant has weight 50000N and sole of its foot is

500 cm2 .

determine:

a. Pressure in elephants

foot if that elephant

stand with one leg

b. Pressure in each foot ifthat elephant stand with

four leg

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