Project • Students should definitely do yoyo lab with

microwaving ivory soap!

Bell Work 11/6 – 4 minStart a new bell work sheet titled “Gas Laws”.

1.If you heat a gas, what happens to it’s volume?

2.Define pressure in your own words.

3.Do you know anyone named Charles? Anyone at all?

Today you are going to…take notes & see cool demos & videos on Charles’ Law and Gay-Lusaac’s Law.

So you can…develop an understanding and ability to predict gases behavior. That way you won’t kill yourself and you’ll improve your gas mileage!

You’ll know you’ve got it when…you can • State both laws and identify their differences and

similarities

Gas Laws & Fluid Principals

Mask!Mask!

REVIEW• Volume

• Temperature

• Pressure

Pressure• Pressure – is the amount of force exerted

per a given area.

• Pressure = force/area– Force - push or pull

• Less area, more pressure– Book flat & sideways– Knife– pressure points

Pressure• bed of nails

• Same force spread over large area, force per nail = 150 lbs/400 nails– Balloon too!

Directly & Inversely Proportional • Directly proportional – increasing or

decreasing together with a constant ratio

• Inversely proportional – increasing or decreasing opposite one another with a constant ratio– Pressure

– Density Equation

Charles’ Law • If pressure is kept constant, the volume of a

gas is directly proportional to its temperature.– Happens in flexible containers– If temp. increases, volume increases– If temp. decreases, volume decreases

Applications of this law:• Hot air balloon

– Charles invented a hydrogen balloon, but that doesn’t work off his law…a hot air balloon does.

• Balloon in hot water!• As air cools in winter, it’s volume decreases

– Add air to car tires. (In summer, you may need to…)

– Don’t leave inflated sports balls outside in the winter. 

• Decreased lung capacity in winter• Backdraft!

– Oxygen reintroduced to burning room, burns more & hot fiery air expands

Charles’ Law continued.• www.youtube.com/watch?v=IkRIKGN3i0k

• Helium balloon in liquid nitrogen – Temp changes from 25oC to -196oC– Volume is 1 L– How much is new volume?

Pressure of a Gas• What is pressure again?

• Pressure of a gas is caused by all the gas molecules bumping into a surface– Air molecules move over 100 mph!– Each air molecule collides with one or another of its

neighbors 10,000,000,000 times per second!!!!– The more often they bump a surface, the more pressure

• Still a force over an area• Look at cool simulation!!

Atmospheric Pressure• 14.7 lbs/in2 at sea level

– The weight of all air above compresses air below, raising air pressure near sea level

• Things move from HIGH to LOW pressure!

• Demos?– License on jar– Straw holds water– Holey bottle (BL)

Gay-Lussac’s Law • If volume is kept constant, the pressure of a

gas is directly proportional to its temperature.– increasing the temperature increases pressure– decreasing the temperature decreases pressure

• Applies to rigid containers of gas (The volume can’t change if container is rigid.)

Gay Lusaac’s Law• Gay Lusaac’s pressure gauge demo

• BLEVE

• Can with water heated then inverted

CAN DEMOCAN DEMO

• What happens to the can? Why?• As can is heated, temperature of the gas inside __________,

so volume _______________• Faster moving particles result in more collisions, which would

increase the pressure if the can were sealed – instead, some particles leave out of the opening of the can. 

• The pressure is kept the same because less, faster moving, particles are needed to get the same number of collisions as before. 

• Can is flipped into cold water, temperature of the gas inside _____________, so the pressure of the gas inside _________________. (__________ law)

• Particles slow down, reducing the number of collisions, reducing the pressure.  The outside pressure is now greater , and it crushes the can.

Cool Videos

• Barrel

• http://www.youtube.com/watch?v=n-3cu_Q119s

• Other thing train

• http://www.youtube.com/watch?v=Zz95_VvTxZM

Gay Lusaac’s Law applications• Never store fire extinguisher close to stove• Never store propane tank near furnace

– Just to be safe, don’t store it inside house.

• Never throw a spray can in a fire.• Heating closed containers in microwave

– Always hold heated containers away from face when opening!

• Cannons & bullets – Extreme heat creates enough pressure to launch

projectile

Gay Lusaac’s Law applications

• CO2 cartridge releasing air

Closure

• Explain the difference between Charles Law and Gay Lussac’s Law

Bell Work 11/7/13

• Define Charles Law and Gay Lusaac’s Law and give 1 demo/application of each.

Today you are going to…take notes & see cool demos & videos on Boyles’ Law, pressure, and Pascal’s Principle.

So you can…develop an ability to predict the behavior of gases and fluids.

You’ll know you’ve got it when…you can • State Boyles’ Law and Pascal’s Principle and list some

applications for them.• Explain the relationship between force, area, and

pressure.

Nurse Boyle!

Boyle’s Law

• If temperature is kept constant, the volume of a gas is inversely proportional to its pressure.– Increasing pressure decreases volume– Decreasing pressure increases volume

OR– Increasing volume decreases pressure– Decreasing volume increases pressure

Boyle’s Law

• Increase pressure on syringe, volume decreases.• Decrease pressure on syringe, volume increases.

Boyle’s Law Applications/DemosIf you squeeze a balloon too hard the pressure will increase and it will POP!

If a tractor trailer truck receives a heavy load, the driver should take time to remove some air pressure from the tires. Why?

Turkey baster, spray cans

Balloon in a syringe

Bell Jar Demosballoon, shaving cream, marshmallows, water in jar, water bottle, heated water,

Boyle’s Law Applications/DemosLungs

http://www.youtube.com/watch?NR=1&v=msphJoHIqiU&feature=endscreen

Muscles move chest out.volume increases, pressure decreases, air is pushed in

Muscles contract chestvolume decreases, pressure increases, pushing air out

Who’s Law?

Can of AirCan of Air

• Which law? – What do we notice?

• As air leaves the can, pressure inside the can ____________, so temperature inside the can ______________.

Bell Work 11/8/13

1. Complete the following chart by filling in “constant”, “directly” or “inversely”.

Law Pressure Volume Temperature

Boyle’s Law

Gay-Lussacs’ Law

Charles’ Law

Missing Work!

• Heating Curve of Water Lab– Tanner, Alida, Tyler?, Josh, Jon, Zach, Zan– Taylor, Nathan, Savannah, Amber, Dominic

• Kinetic Theory of Matter Test– Destiny– Dom, Swan, Amber

• http://www.youtube.com/watch?v=yVTN8BGe4-s

• Add inclined plane so goes up!

Pascal’s Principle

• Pascal’s Principle- pressure applied at one point of an enclosed fluid is transmitted equally in all directions. – Pass around demonstrator!– That’s why bubbles are spherical!

Applications of Pascal’s Principle• Pascal’s principal can be used to:

1. Transmit a force • Toothpaste – squeeze here, it comes out there!• Car breaks

Pascal’s continued..• Pascal demonstrator – students will examine and Pascal demonstrator – students will examine and

explore.explore.

– Observations?

Pascal’s Principle• Hydraulics- lifting objects by squeezing a

fluid in an enclosed system.– since pressure is equal everywhere, when the

pressure of the fluid is transmitted to a larger area, the force is multiplied.

• Since gases compress, liquids work better

– You gain force, but you lose _______. • http://www.youtube.com/watch?v=A3ormYVZMXE&feature=related

Applications of Pascal’s Principle• Pascal’s principal can be used to:

2. Multiply a force• Hydraulic jacks• Heavy machinery/equipment• Breaks• Water guns (both Boyles’ Law & Pascal’s Principal)

Bell Work 11/6/121. What’s Pascal’s Principal say?

Units of Pressure

• Pascal (Pa) – unit of pressure• Pounds per square inch (psi or lb/in2) • 1 Pa = 1 N/m2

1.0000 Pa = 0.000145 psi (that’s reeeaaaly small!!)1.0000 kPa = 0.145 psi1 atmosphere = 14.7 psi = 101.3 kPa

According to Mr. Shuster, your feet 1-5 psi when flatfooted

Pascal Problem OneExplain subscripts!!!Explain subscripts!!! Make triangle!!!Make triangle!!!

A1 = 10 in2 A2= 1,000 in2

F1 = 15 lb F2 = ?

P = ? psi

Pascal Problem TwoA1 = 8.0 in2 A2= 1440 in2

F1 = 30.0 lb F2 = ?

P = ? psi

Pascal Problem Three!A1 = 8.0 m2 A2= 24 m2

F1 = 50.0 N F2 = ?

P = ?

Pascal Problem FourA1 = 2.0 m2 A2= 80.0 m2

F1 = 30.0 N F2 = ?

P = ? psi

A1 = 10 cm2 F1 = 50 N

A2= 35 cm2 F2 = ?

P = ?

A1 = 10 cm2 F1 = 50 N

A2= 35 cm2 F2 = ?

P = ?

A1 = 7 cm2 F1 = 155 N

A2= 98 cm2 F2 = ?

P = ?

A1 = 7 cm2 F1 = 155 N

A2= 98 cm2 F2 = ?

P = ?

• Things move from high pressure to lower pressure. 

Bernoulli’s Principle

• As the velocity of a fluid increases, the pressure exerted by the fluid decreases.– Objects always move from areas of high

pressure to areas of low pressure.

Examples of Bernoulli’s Principle.• Blow across the top of a paper, What do you think will

happen? What actually happens?

• Take two sheets of paper and blow between them. What do you think will happen? What actually happens?

• 2 POP CANS

• textbook demo

• Ping pong ball– Pipe n Styrofoam ball

• Vacuum and bigger ball

• Trains & boats passing, Truck passing car

• Julius Sumner Miller

• This site shows the effect of smaller area has on the speed of the particles.

QUESTION!

• Objects move from areas of high pressure to lower

• How does the shape of an airplane’s wing enable it to fly? pressure.

Applications of Bernoulli’s Principle.

• Bernoulli’s principle explains why airplanes fly. The wing of an airplane is curved so that the air goes faster over the top of the wing. This reduces the air pressure on top of the wing. The greater air pressure below lifts the airplane up.

• http://www.youtube.com/watch?v=sQnCD7p3CrU&feature=related

• This site contains a 10 minute video illustrating Bernoulli's Principle as it relates to flight

Applications of Bernoulli’s Principle.

• Curveball

• Frisbee

• Boomerang

• Tube spun around moves paper holes

Discussion

• Briefly discuss Archimedes other accomplishments- the water screw, the claw, simple machines, mirrors and lenses. (students are not responsible for this info.)

Archimedes’ Principle

• Buoyant force – force of liquid pushing something up

• Holds you up when you’re swimming• Makes things underwater lighter!

Archimedes’ Principle

• The buoyant force on an object in a fluid is equal to the weight of the fluid that the object displaces. • Buoyant force = weight of displaced fluid

• Demo of Archimedes’ Principal by Professor– http://www.youtube.com/watch?

v=g6aErhwFXsg&feature=related

Archimedes's Principle• As an object sinks into the fluid, there is more

fluid displaced by the object, increasing the upward buoyant force acting on the fluid.

• Demo?Demo?

• Video demo!

If the object has a weight of 12 lbs, how many lbs of water was displaced?

? Lb Water

If the object has a weight of 12 lbs, how many lbs of water was displaced?

Archimedes Principle

• So, Why do some objects float in water?• Objects that are more dense than water ______

• Objects that are less dense than water___________    

• If something is floating, it is displacing exactly it’s weight in water! – object floats if buoyant force = weight of object

• Buoyancy - ability for things to float.

Archimedes Principle

• Why can a heavy ship float?How much water does a 2 ton boat displace?

• So how was this principle discovered?– http://www.youtube.com/watch?v=ZUYkBeAW5hc&feature=related  

Archimedes Principle

• If a 50 lb kid gets onto a boat, how much will it sink? (Enough to dis…)– Aluminum boat in sulfur hexafluoride

• Water has a “density” of 8.34 lb/gallon. How many gallons of water would a 150 lb person displace?

• Mercury has a “weight density” of 113 lb/gallon. How many gallons of mercury would a 150 lb person displace?

– Use different fluids, like mercury, air, sodium hexafluoride – Do example – something in alcohol & something in salt water!– Drop graduated cylinder in water!

Who is this?

Who is this?

Fun Fact!

END

Hydrometer

• Use to measure density of liquids directly• Used in fish tanks & wine making

• http://www.ehow.com/video_5226052_use-hydrometer-fish-tanks.html

Bell Work 10/30/121. Pressure and volume are inversely related.

2. Volume and temperature are directly related.

3. Pressure and temperature are directly related.

4. Moving fluids have less pressure.

5. Buoyant force = weight of water displaced

6. Pressure in an enclosed fluid is transferred without changing

7. When we change the pressure, volume, or temperature of a gas, does it’s mass change? Do the number of particles change?

Bell Work 11/1/121. What causes pressure exerted by gas molecules?

(What are the molecules doing?)

2. When scientists record the volume of a gas, why do they also record the temperature and pressure.

3. As the temperature of a gas increases, what happens to particle speed? What happens to volume if it is in a flexible container? What happens if it’s in a rigid container and volume can’t increase?

Bell Work 11/2/121. A closed water bottle (with just air in it) is put into the

freezer. What will happen , why, and what law is this?

2. 10 years from now it’s Thanksgiving day and Victoria Fox is cooking turkey for the fam. Suddenly the fire extinguisher above the stove explodes! Why, and what law is this?

• Matt throws a 20.0 lb rock into the water. If it displaces 12.0 lbs of water, how much will the rock weigh underwater?

• Who’s principle?

• Egg on bottle– As the paper in the bottle burns, the gases inside

the bottle are heated. – The volume of the air in the bottle increases, the

bottle increases with temperature, causing some of the gases to be forced out past the egg. This is ______________’s law

– When the flame burns out, the temperature

decreases, causing pressure inside the bottle to decrease.

– This is ______________’s law– There is _________ pressure on the outside of the flask

pushes the egg into the bottle (lower pressure).

Egg on bottle• As the paper in the bottle burns, the air inside the

bottle is heated, causing the volume of the air to ______________. This is ______________’s law

• Some of the gases are forced out past the egg, therefore some air has left the bottle.

• When the flame burns out, the temperature

______________, causing pressure inside the bottle to ______________.

• This is ______________’s law• There is _________ pressure on the outside of the

flask pushes the egg into the bottle (_________ pressure).

Bottom of Bottle Example

http://www.youtube.com/watch?v=epOwdGIDzlY&feature=related

Bell Ringer 10/20 – 3 min

1. What principle is being applied to lift the car?

Pascal Problem One

A1 = 10 cm2 F1 = 50

A2= 60 cm2 F2 = ?

Pascal Problem Two

A1 = 15 cm2 F1 = 200 N

A2= 85 cm2 F2 = ?

Bell Ringer 10/21/11A1 = 13 cm2 F1 = 70 N

A2= 39 cm2 F2 = ?

P = ?

Check Homework!

Archimedes's PrincipleUpward buoyant force = weight of the fluid displaced by the

object. 

Change in weight = weight of the fluid displaced by the object. 

Bell Ringer 10/26

1. Use Archimedes’ Principal to determine how many lbs the object weighs out of water. (bottom right)

2. One penny has a weight of 0.0274 N. What was the buoyant force on your boat just before it sunk?

2 Lb Water

How much does this object weigh?

• What’s the magnitude of buoyant force?

5 Lb Water