Pressure.notebook

1

January 31, 2016

Jan 2010:46 PM

Pressure Notes #1 &

Demonstrations

FLUID PRESSURE.pptx

Jan 128:42 PM

Flaming Vapor Ramp

Physical Properties Chemical Propertiesliquid, clear, odor, density > air ability to burn 

Physical Changes Chemical Changesliquid to gas: vaporization burns (flammability)

• Fluids flow• Gases and liquids are fluids

FLUID PRESSURE

Or feeling a bit stressed lately???

Are you under a lot of pressure?Do you feel a lot of pressure?

PRESSURE!

Right now, 1000 N of pressure are pushing on the top of your head!

What is pressure?

The result of a force distributed over an area

Pressure = force = Newton

area meters2

SI unit of pressure is the pascal (Pa)

1 Pa = 1 newton/m2

Atmospheric Pressure

The atmosphere is the thin layer of nitrogen, oxygen, and other gases that surrounds Earth.

Atmospheric pressure is the pressure caused by the weight of the atmosphere.

Atmospheric pressure is exerted on everything on Earth, including you.

Atmospheric Pressure

The air inside this balloon exerts pressure that keeps the balloon inflated against atmospheric pressure.

In the image below, the force of the air particles hitting the inner surface of the tire creates pressure, which keeps the tire inflated.

So what are fluids?

Substances that flow and have no definite shape

Examples: gases and liquids

Fluids Exert Pressure

A fluid is any material that can flow and that takes the shape of its container. Fluids include liquids and gases.

All fluids exert pressure, which is the amount of force exerted per unit area of a surface.

Fluids Exert Pressure, continued

Pressure and Bubbles Soap bubbles get rounder as they get bigger because fluids exert pressure evenly in all directions.

Since air is a fluid, adding air to an air bubble causes it to expand in all directions at once.

Fluids want to . . .

Move from areas of high pressure to areas of low pressure

Everything wants to be equal

Pressure Differences and Fluid Flow

Just by drinking through a straw you can observe an important property of fluids: Fluids flow from areas of high pressure to areas of low pressure.

Fluids Exert Pressure, continued

Calculating Pressure Pressure can be calculated by using the following equation:

pressure

=

force

area

The SI unit for pressure is the pascal. One pascal (1 Pa) is the force of one newton exerted over an area of one square meter (1 N/m2).

Examples

If the area of a box touching the ground is 1.5 square meters, and its weight is 2700 newtons, what pressure does the box exert on the ground?

A gymnast standing on one hand (area 0.02 m2) pushes down on the ground with a force of 600 N. How much pressure does the gymnast exert on the ground?

So . ……..

The greater the area the force is distributed over, the less the pressure

For example: sharp knife vs dull knife

Sharp knife exerts a LARGE FORCE over a small area

FORCE/ area = PRESSURE

Dull knife exerts a small force over a LARGE AREA

Force/AREA = pressure

You do the math

Sharp knife: area = 1 mm2

Dull knife: area = 5 mm2

Force applied to each knife = 5 N

Sharp knife = 5/1 = 5N/m2

Dull knife = 5/5 = 1N/m2

How about?

Soft Bed vs. hard floor

Bed exerts force upward equal to your weight

Mattress exerts force upward over your whole body

Floor only pushes on pressure points which are touching the floor

Another example:

Ice skating (or roller blading)

A shoe distributes the force (body weight) over a much larger area than the skate

So the skate exerts a much higher pressure on the ice than the shoe does

The skate pushes into the ice and

Voila! You can skate!

Depth effects pressure

As depth increases, water pressure increases

(directly proportional)

Altitude effects pressure

As altitude increase, air pressure decreases

(inversely proportional)

Pressure Differences and Tornadoes The air pressure inside a tornado is very low. Because the air pressure outside of the tornado is higher than the pressure inside, air rushes into the tornado.

The rushing air causes the tornado to be like a giant vacuum cleaner.

Standard atmospheric pressure = 14.7 pounds per square inch

What happened to this can?

Everything wants to be equal!

Pressure on the outside >>>> pressure on the inside

So when the can is heated, the can is crushed!

Why?????

What are some characteristics of pressure in fluids?

PRESSURE!!!

SMART Notebook

Pressure.notebook

2

January 31, 2016

Jan 128:28 PM

Cup and Card

Pressure outside cup is higher than inside the cup.

Jan 128:21 PM

Rising H2O, Dying Flame

• Candle heats air in flask, air expands

• Flame goes out (O2 used up)

• Air cools & condenses, creating lower pressure (vacuum)

Pressure.notebook

3

January 31, 2016

Jan 128:31 PM

Egg in a Bottle

• Higher pressure outside the container pushes the egg into the bottle.

• Alka Seltzer creates gas, increases pressure in the container. Pressure outside container is lower. High pressure in container pushes the egg out.

Jan 128:33 PM

Juice Falls

Depth, Pressure

Depth, Pressure

Directly Proportional

Pressure.notebook

4

January 31, 2016

Jan 128:38 PM

Expando, Contracto

Heat flask, increase gas pressure

Cool flask, decrease gas pressure

Jan 128:34 PM

Bed of Nails

Pressure.notebook

5

January 31, 2016

Feb 610:53 PM

Magic Fountain

Jan 128:40 PM

Pouring a Gas

Pressure.notebook

6

January 31, 2016

Feb 98:04 PM

What would hurt more, (exert a higher pressure?stepping on your toes?

A 5,000 N elephant whosefoot is 750 cm2

A 575 N woman in heels with an area of 1 cm2

Attachments

States of Matter PP snowflake.ppt

FLUID PRESSURE.ppt

FLUID PRESSURE.pptx

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WHAT DO YOU KNOW ABOUT STATES OF MATTER?

What are the three commonly known states of matter?

What is the gas, liquid and solid form of water?

How does matter change state?

Watch this animation on states of matter (click “Play Video”):

Animation: States of Matter

http://teacher.scholastic.com/activities/studyjams/matter_states/

Scholastic

*

Each of these states is also called a phase.

There are three common states of matter: solid, liquid, and gas.

States of matter

are the

physical forms

a substance

can take.

WHAT ARE STATES OF MATTER?

*

THE THREE COMMON STATES OF MATTER

Most substances, like water, can exist in all three states.

A cloud is made of water vapor, a type of gas.

An iceberg is made

of water in solid form.

This glass contains liquid water.

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SOLIDS

Solids have a definite shape and volume, or amount of space an object takes up.

Solid particles vibrate in place but cannot move from their position, which is why solids maintain their

rigid shape.

The particles that make up a solid are packed tightly and held together by strong forces.

*

LIQUIDS

The particles that make up a liquid are spaced farther apart and are held together by weaker forces than solids.

Liquids have a definite volume but not a definite shape.

Liquid particles move slightly, which allows liquids to flow and take the shape

of the container they are in.

*

GASES

Gases do not

have a definite volume or shape.

Gas particles move freely and will expand to fill a container of any size or shape.

The particles that make up a gas are fast-moving and are held together by extremely weak forces.

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CHANGES OF STATE

Matter can change from one state to another.

Even though the physical form of the matter changes, it remains the same substance.

Changes of state occur when thermal energy (heat energy) is absorbed or released by a substance.

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WHAT ARE THE CHANGES OF STATE?

GAS

SOLID

LIQUID

Deposition

Sublimation

Boiling / Evaporation

Condensation

Freezing

Melting

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HOW DOES MATTER CHANGE STATE?

As heat increases,

a substance changes from a solid to a liquid, and finally to a gas.

As heat decreases,

a substance changes from a gas to a liquid,

and finally to

a solid.

Thermal Energy Added

Temperature

Changes of State

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Kinetic Theory

All matter is in constant motion.

Kinetic Energy: Energy an object has due to its motion

The particles that make up matter are in constant motion and have a force of attraction for each other.

Solid

Gas

Liquid

DISCUSSION QUESTIONS

How does pressure and temperature affect the state of water, carbon dioxide, and hydrogen?

On Earth, we typically see gases, liquids, and solids. But is there a fourth state of matter?

Use this interactive PBS Web site to find out:

www.pbs.org/wgbh/nova/zero/matt-flash.html.

Learn about a fourth state of matter at this Web site:

http://www.spaceweathercenter.org/amazing_plasmas/02/02.html

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HANDS-ON SCIENCE

(No Lab Required)

Directions

Place chocolate chips and candy-coated chocolate in separate bags.

Place each bag of chocolate in a half-filled mug of room-temperature water.

Your teacher will continue to increase the temperature in each mug by adding

boiling water a little at a time.

As a class, monitor the temperature with a thermometer until the chocolate starts to melt in the bag.

This demo explores melting points.

Materials

chocolate chips, candy-coated chocolates, baggies, two mugs, water, thermometer

Conclusion

At what temperature does each type of chocolate start to melt? Why do you think this is?

*

SMART Notebook

FLUID PRESSURE

Or feeling a bit stressed lately???

Are you under a lot of pressure?

Do you feel a lot of pressure?

PRESSURE!

Right now, 1000 N of pressure are pushing on the top of your head!

What is pressure?

The result of a force distributed over an area

Pressure = force = Newton

area meters2

SI unit of pressure is the pascal (Pa)

1 Pa = 1 newton/m2

Atmospheric Pressure

The atmosphere is the thin layer of nitrogen, oxygen, and other gases that surrounds Earth.

Atmospheric pressure is the pressure caused by the weight of the atmosphere.

Atmospheric pressure is exerted on everything on Earth, including you.

Atmospheric Pressure

The air inside this balloon exerts pressure that keeps the balloon inflated against atmospheric pressure.

In the image below, the force of the air particles hitting the inner surface of the tire creates pressure, which keeps the tire inflated.

So what are fluids?

Substances that flow and have no definite shape

Examples: gases and liquids

Fluids Exert Pressure

A fluid is any material that can flow and that takes the shape of its container. Fluids include liquids and gases.

All fluids exert pressure, which is the amount of force exerted per unit area of a surface.

Fluids Exert Pressure, continued

Pressure and Bubbles Soap bubbles get rounder as they get bigger because fluids exert pressure evenly in all directions.

Since air is a fluid, adding air to an air bubble causes it to expand in all directions at once.

Fluids want to . . .

Move from areas of high pressure to areas of low pressure

Everything wants to be equal

Pressure Differences and Fluid Flow

Just by drinking through a straw you can observe an important property of fluids: Fluids flow from areas of high pressure to areas of low pressure.

Fluids Exert Pressure, continued

Calculating Pressure Pressure can be calculated by using the following equation:

The SI unit for pressure is the pascal. One pascal (1 Pa) is the force of one newton exerted over an area of one square meter (1 N/m2).

pressure

=

force

area

Examples

If the area of a box touching the ground is 1.5 square meters, and its weight is 2700 newtons, what pressure does the box exert on the ground?

A gymnast standing on one hand (area 0.02 m2) pushes down on the ground with a force of 600 N. How much pressure does the gymnast exert on the ground?

So . ……..

The greater the area the force is distributed over, the less the pressure

For example: sharp knife vs dull knife

Sharp knife exerts a LARGE FORCE over a small area

FORCE/ area = PRESSURE

Dull knife exerts a small force over a LARGE AREA

Force/AREA = pressure

You do the math

Sharp knife: area = 1 mm2

Dull knife: area = 5 mm2

Force applied to each knife = 5 N

Sharp knife = 5/1 = 5N/m2

Dull knife = 5/5 = 1N/m2

How about?

Soft Bed vs. hard floor

Bed exerts force upward equal to your weight

Mattress exerts force upward over your whole body

Floor only pushes on pressure points which are touching the floor

Another example:

Ice skating (or roller blading)

A shoe distributes the force (body weight) over a much larger area than the skate

So the skate exerts a much higher pressure on the ice than the shoe does

The skate pushes into the ice and

Voila! You can skate!

Depth effects pressure

As depth increases, water pressure increases

(directly proportional)

Altitude effects pressure

As altitude increase, air pressure decreases

(inversely proportional)

Pressure Differences and Tornadoes The air pressure inside a tornado is very low. Because the air pressure outside of the tornado is higher than the pressure inside, air rushes into the tornado.

The rushing air causes the tornado to be like a giant vacuum cleaner.

Standard atmospheric pressure = 14.7 pounds per square inch

What happened to this can?

Everything wants to be equal!

Pressure on the outside >>>> pressure on the inside

So when the can is heated, the can is crushed!

Why?????

What are some characteristics of pressure in fluids?

PRESSURE!!!

SMART Notebook

FLUID PRESSURE

Or feeling a bit stressed lately???

Are you under a lot of pressure?Do you feel a lot of pressure?

PRESSURE!

Right now, 1000 N of pressure are pushing on the top of your head!

What is pressure?

The result of a force distributed over an area

Pressure = force = Newton

area meters2

SI unit of pressure is the pascal (Pa)

1 Pa = 1 newton/m2

Atmospheric Pressure

The atmosphere is the thin layer of nitrogen, oxygen, and other gases that surrounds Earth.

Atmospheric pressure is the pressure caused by the weight of the atmosphere.

Atmospheric pressure is exerted on everything on Earth, including you.

Atmospheric Pressure

The air inside this balloon exerts pressure that keeps the balloon inflated against atmospheric pressure.

In the image below, the force of the air particles hitting the inner surface of the tire creates pressure, which keeps the tire inflated.

So what are fluids?

Substances that flow and have no definite shape

Examples: gases and liquids

Fluids Exert Pressure

A fluid is any material that can flow and that takes the shape of its container. Fluids include liquids and gases.

All fluids exert pressure, which is the amount of force exerted per unit area of a surface.

Fluids Exert Pressure, continued

Pressure and Bubbles Soap bubbles get rounder as they get bigger because fluids exert pressure evenly in all directions.

Since air is a fluid, adding air to an air bubble causes it to expand in all directions at once.

Fluids want to . . .

Move from areas of high pressure to areas of low pressure

Everything wants to be equal

Pressure Differences and Fluid Flow

Just by drinking through a straw you can observe an important property of fluids: Fluids flow from areas of high pressure to areas of low pressure.

Fluids Exert Pressure, continued

Calculating Pressure Pressure can be calculated by using the following equation:

pressure

=

force

area

The SI unit for pressure is the pascal. One pascal (1 Pa) is the force of one newton exerted over an area of one square meter (1 N/m2).

Examples

If the area of a box touching the ground is 1.5 square meters, and its weight is 2700 newtons, what pressure does the box exert on the ground?

A gymnast standing on one hand (area 0.02 m2) pushes down on the ground with a force of 600 N. How much pressure does the gymnast exert on the ground?

So . ……..

The greater the area the force is distributed over, the less the pressure

For example: sharp knife vs dull knife

Sharp knife exerts a LARGE FORCE over a small area

FORCE/ area = PRESSURE

Dull knife exerts a small force over a LARGE AREA

Force/AREA = pressure

You do the math

Sharp knife: area = 1 mm2

Dull knife: area = 5 mm2

Force applied to each knife = 5 N

Sharp knife = 5/1 = 5N/m2

Dull knife = 5/5 = 1N/m2

How about?

Soft Bed vs. hard floor

Bed exerts force upward equal to your weight

Mattress exerts force upward over your whole body

Floor only pushes on pressure points which are touching the floor

Another example:

Ice skating (or roller blading)

A shoe distributes the force (body weight) over a much larger area than the skate

So the skate exerts a much higher pressure on the ice than the shoe does

The skate pushes into the ice and

Voila! You can skate!

Depth effects pressure

As depth increases, water pressure increases

(directly proportional)

Altitude effects pressure

As altitude increase, air pressure decreases

(inversely proportional)

Pressure Differences and Tornadoes The air pressure inside a tornado is very low. Because the air pressure outside of the tornado is higher than the pressure inside, air rushes into the tornado.

The rushing air causes the tornado to be like a giant vacuum cleaner.

Standard atmospheric pressure = 14.7 pounds per square inch

What happened to this can?

Everything wants to be equal!

Pressure on the outside >>>> pressure on the inside

So when the can is heated, the can is crushed!

Why?????

What are some characteristics of pressure in fluids?

PRESSURE!!!

SMART Notebook

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