Unit 3Fluids & Dynamics

Chapter 7 -- Kinetic Molecular Theory

Chapter 8 --Fluids are affected byforces, pressure, and heat

Chapter 9 -- Natural and Constructed fluid systems

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Chapter 7

Mix and Flow of Matter

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7.1 States of Matter

• Matter is anything that has mass and volume.

• Mass is the quantity of matter a substance or object contains. Mass is usually measured in grams (g) or

kilograms (kg).

• Volume is the amount of space taken up by a substance or object. Volume is usually measured in millilitres

(mL), litres (L), or cubic centimetres (cm3).

See pages 246 - 247

Comparing the basketball and bowling ball, which has more mass? Volume?

3

7.1 States of Matter

The four familiar states (phases) of matter.

See pages 246 - 247

Fixed mass Fixed Volume Fixed Shape

Solid Yes Yes Yes

Liquid Yes Yes No

Gas Yes No No

Plasma Plasma exists on earth as lightning, auroras, and neon. Exists due to nuclear fusion.

solid liquid gas plasma4

The Particle Model of Matter

• All matter is made of small particles that are too small to see.

• There are spaces between the particles. The amount of space varies depending upon the state.

• The particles are always moving.• The particles are attracted to one another.• Plasma is not commonly talked about in the Particle

of model of matter.

See page 2485

The Kinetic Molecular Theory

• Kinetic energy is the energy due to motion.

• The Kinetic Molecular Theory (KMT) explains what happens to matter when the kinetic energy of the particles changes. A theory provides a scientific

explanation based on the results of experimentation.

See page 249

As the rollercoaster’s speed increases, its kinetic energy also increases.

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The Kinetic Molecular Theory

The main points of the kinetic molecular theory include:

See page 249

1. All matter is made of very small particles.2. There is empty space between particles.3. Particles are constantly moving. The particles are

colliding with each other and the walls of their container.4. Energy makes particles move. The more energy the

particles have, the faster they move and further apart they get.

Solid: Particles are so tightly packed together they cannot move freely. They can only vibrate.

Liquid: Particles are farther apart and they can move by sliding past each other.

Gas: Particles are very far apart and move around quickly.

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Homework

Pg# 249 #1-5

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Thermal Expansion and Contraction

• Thermal expansion is the increase in volume of a substance when its temperature is raised.

• Thermal contraction is the decrease in volume of a substance when its temperature is lowered.

See page 250

Can you use the concepts of thermal expansion and contraction to explain how a thermometer works?

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The Difference Between Heat and Temperature

• Thermal energy is the total kinetic energy of all the particles in the substance.

• Heat is the transfer of thermal energy between two material of different temperature. Heat is always transferred from the

substance with a higher temperature to the substance of a lower temperature.

• Temperature is the average kinetic energy of the particles in a substance.

See page 25110

Changes of State

See pages 252 - 253

Name Change of State(from _ to _)

Heat Gained Heat Lost

Melting Solid to liquid

Evaporation Liquid to gas

Condensation Gas to liquid

Solidification Liquid to solid

Sublimation Solid to gas

Deposition Gas to solid

•Melting point is the temperature at which solid turns to liquid.•Boiling point is the temperature at which liquid turns into gas. 11

Changes of State

See pages 252 - 253Take the Section 7.1 Quiz

Solid

Melting

Liquid

Boiling

Gas

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7.2 Fluids and Density

A fluid is any form of matter that can flow. Liquids and gases are fluids since they do not have a fixed

shape. Solids are not fluids.

See page 260Lava, water, and syrup are examples of fluids.

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Solid, Liquid, and Gas Density

Density is the amount of mass for each unit of volume. Density describes how closely

packed together the particlesare in a material.

See page 261

Describe the spacing of the particles in the solid block, liquid water, and gaseous air.

Most substances are denser in their solid form than in their liquid form, but water is an exception.

14

Layers of Fluids

Fluids that do not mix, layer themselves according to their density.

Less dense fluids “float” on top of more dense fluids.

See pages 262 - 263

Can you list the objects, in this beaker, from most dense to least dense?

oil

ball

water

15

Measuring Density

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Measuring Density

See page 264

Both mass and volume are required when calculating density.

Mass: Mass can be measured using a scale or

balance.

Volume: For objects that are block shaped, volume can

be calculated by measuring the block and then using the equation:

volume = length x width x height.

For objects with irregular shape displacement is the method used to find the volume.

balance

17

Calculating Density

See page 265

Density can be calculated using the following formula:

Answer the following:What is the density of a 4 cm3 rock that

has a mass of 24 g?

A 5 ml sample of motor oil has a mass of 4.5 g. What is the density of the motor oil?

See next slide for the answers. 18

Calculating Density

See page 265

Density can be calculated using the following formula:

Answer the following:What is the density of a 4 cm3 rock that

has a mass of 24 g?

A 5 ml sample of motor oil has a mass of 4.5 g. What is the density of the motor oil?

Answers• 6 g/cm3

• 0.9 g/mL

Take the Section 7.2 Quiz 19

Homework

Pg# 272 + 273

Checking Concepts

#1-8, 13-15

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8.1 Forces

A force is a push or pull that acts on an object. Forces can change the motion

of an object. Forces can change the shape of

an object.

See page 276

The force applied by the bat can change the motion of the ball.

Applying a force to an object can cause it to change shape.

21

Types of Forces

Two categories of forces

Forces that touch an object are called contact forces. Tension – force in a wire or rope Friction – slows down motion Elastic – spring-like object restores itself to its normal shape.

Applying a force without contact are called action-at-a-distance forces. Gravitation – attraction between masses. Electrostatic – force between charged objects Magnetic – acts on certain metals

See pages 277 - 278

Tension force during a game of “tug-a-war”

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Measuring Mass

Mass is measured in kilograms (kg). 1000 grams (g) = 1 kilogram (kg).

Mass is best measured using a balance scale.

Mass does not depend upon the amount of gravity.

Weight is the amount of force on an object due to gravity.Different Planets with different gravities

Fg= Force or Weight Fg= m x gm= massg= Gravitational Constant; 9.8m/s on Earth

See page 27923

Weight Depends on Gravity

See page 280

• Weight is the amount of force on an object due to gravity. The amount of force depends on the

amount of gravity.

• The measuring unit of force is the newton (N).

A D-cell battery weighs about 1 N.

A typical carton of milk weighs about 10 N.

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Measuring Force

See pages 282 - 283

Force meters usually include a spring or similar elastic device that stretches or compresses.

Common force meters are called newton gauges or spring scales.

1 kg of mass would have a weight (force of gravity) of 9.8 N on Earth. Multiply mass by 9.8 m/s2 to get the

weight of the object on Earth.Spring scale

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Forces and Motion

• Balanced forces are equal in strength but opposite in direction.

• Object will remain stationary or keep moving at a constant speed and direction. Net force is zero.

• Unbalanced forces cause a change in the speed or direction of an object.

• Object starts to move, if it is pushed or pulled. Net force is not zero.

See pages 284 - 285Take the Section 8.1 Quiz

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8.2 Pressure

• Pressure is the amount of force applied over a given area on an object.

• When pressure is applied to matter, compression can result.

• Compression is a decrease in volume produced by a force.

See page 290

The tennis racket applies a force to the ball. The resulting pressure causes the ball to compress.

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Gases Are Compressible

A gas can easily be compressed because there is a large amount of space between its particles. Gas that is trapped in a container and heated

will increase in pressure. Heat causes the particles to move faster.

These fast moving particles bounce off the sides of the container.

The increased pressure could cause the container to explode.

Gas that is trapped in a container and cooled will decrease in pressure. The decreased pressure could cause the

container to implode.See page 291 - 292

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ExplosionExplosion

ImplosionImplosion

H.P.

H.P.

L.P.

L.P.

Liquids and Solids Are Very Difficult to

CompressThe particles of liquids and solids are already so tightly

packed together that squeezing them together is almost impossible.

Solids and liquids are described as incompressible.

See page 293

A bottle filled with gas

When force is applied to the bottle, the gas particles move closer together. The gas is compressed into a smaller volume.

A bottle filled with liquid

When force is applied to the bottle, the liquid does not compress. There is no room for the liquid particles to move closer together 29

Compression and Deformation

See pages 293 - 294

Solids can appear to be compressed if the “air pockets” in the material are compressed. An example would be squishing

(compressing) a marshmallow.

Solids can also appear to be compressed when they are deformed.

Deformation means to change shape without being forced into a smaller volume. A ball hitting a solid surface is an example

of deformation.

The player’s face and the ball are temporarily compressed and deformed.

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Comparing Pressure

Pressure depends on both the amount of force and also the area the force acts upon.Formula for pressure:

1 newton (N) of force for every square metre of area (m2) is called a pascal (Pa).

1000 Pa = 1 kPaSee page 295

Air pressure can be measured using a simple wet barometer as shown.

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Calculating Pressure

• Use the above formula to calculate the pressure involved in the following questions.

• An 880 N person stands on a 0.80 m by 1.2 m board.

• A 52 000 N car rests on a 3.0 m by 6.0 m platform.

See page 296

Go to the next slide to check your

answers

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Calculating Pressure

Use the above formula to calculate the pressure involved in the following questions.

An 880 N person stands on a 0.80 m by 1.2 m board. (920 Pa)

A 52 000 N car rests on a 3.0 m by 6.0 m platform. (2900 Pa)

See page 296

Since the clown’s weight is spread out over many nails, the pressure at each nail is small.

Take the Section 8.2 Quiz 33

8.3 Viscosity, Adhesion, and Cohesion

Viscosity is the resistance of a fluid to flow.

Some fluids flow more easily than others because: Particles of different fluids have different

shapes. Particles in some fluids are attracted to each

other more strongly.

The flow rate is the speed at which a fluid flows from one point to another. The slower the flow rate the greater the

viscosity. See pages 300 - 301

Oil has a larger viscosity than water, therefore oil has a slower flow rate.

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The Effect of Temperature on Viscosity

Temperature effects the viscosity of materials as follows:

Liquids Heated viscosity decreases Cooled viscosity increases

Gases Heated viscosity increases Cooled viscosity decreases

See page 302

Temperature effects how easily a liquid pours.

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Adhesion and Cohesion

Adhesion and cohesion affect the flow rate of liquids.

Adhesion is the attraction of two different objects or fluids to each other.

Cohesion is the strength with which the particles of an object or fluid attract each other.

Surface tension is the property of a liquid in which the surface of the liquid acts as a thin skin due to cohesion.

See pages 304 - 305

Take the Section 8.3 Quiz

The water’s surface tension allows this insect to remain supported.

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9.1 Fluids Under Pressure

Fluids always move from high pressure to low pressure Fluids under pressure and compressed gases are used for a

variety of everyday tasks

Air molecules pulled by gravity = atmospheric pressure Air pressure increases as altitude decreases

The more air there is above, the more it compresses the air molecules below

Air pressure is lower at high altitudes When humans change altitude, our

bodies try to equalize the pressure differences by having our ears “pop”

See pages 314 - 31637

Pressure Differences

Fluids will always attempt to move from high pressure to low pressure When we drink with a straw, we first remove

air from the closed straw, which lowers the pressure inside. The atmosphere, having a higher pressure, then tries to get into the straw, and pushes the fluid up and out of the way to try to get into the straw!

See page 316

This same idea is used for

many purposes, including

hydraulics, water rockets and

dental tools. 38

Liquid Pressure and Buoyancy

The pressure of fluids increases with depth When you dive deep, you can feel more pressure In Earth’s atmosphere and oceans, pressure also increases with

depth (air behaves like as fluid as well!) Sea level is about the “deepest” the atmosphere gets• Sea level = 1 atmosphere = 101.3 kPa (kilopascals)• Top of Mount Everest = 1/3 atm = 330 kPa• From sea level, every 10 m in water depth = +1 atm• A submarine at a depth of 500 m has the equivalent of a 500

000 kg object resting on every square metre!• Buoyancy refers to low density floating on high density

The amount a fluid allows objects to float = buoyant force

See page 31739

• Many vehicles, including submarines, airplanes and space shuttles all must consider pressure changes Submarine designers must

ensure the sub is safe design a way to change depths

When water is pumped in, density increases = sink

When water is pumped out,density decreases = rise Compressed air, kept onboard, pushes out water

• Convection refers to the movement of low density over top of high density fluids

Rising and Sinking

See page 318

Take the Section 9.1 Quiz40

9.2 Constructed Fluid Systems

By controlling fluids, humans attempt to do work or protect development. Hydraulics = create pressure in liquids to do work Pneumatics = create pressure in gases to do work Humans attempt to control natural water movements

through the use of pumps and barriers like levees.

See page 324

By using pumps and levees, New Orleans is usually kept dry. When Hurricane Katrina overwhelmed their fluid-control systems, however, tragedy occurred.

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Fluids at Rest and in Motion

Fluids at rest Pascal discovered the concept of static pressure Squeezing a fluid at one point transmits force everywhere Static pressure is created when an enclosed fluid is squeezed

Static pressure can then apply a force somewhere else• Eg. Squeezing a tube of toothpaste, brakes on a car

Fluids in motion Bernoulli discovered the

concept of dynamic pressure Fluids in motion cause

a decrease in pressure perpendicular to the direction of motion

Dynamic pressure is created when fluid moves See pages 325 - 326

Air moving faster over the wing creates higher pressure underneath = lift force

42

Hydraulic Systems

Hydraulics = study of pressure in liquids Hydraulic systems create pressures that travel through a

fluid Pressure applied to an enclosed fluid creates a force that can

be used anywhere A pump is generally used to provide pressure at one point

Everywhere in the system than has a usable force• This is why we have pressure in our taps and faucets

Pumps may create high or low pressure to move fluids

See pages 326 - 327

A pump (top) first creates low pressure to draw water in, then high pressure to pump it out.

Low P

High P 43

Valves and Hydraulic Multiplication

Hydraulics = using pressure in Liquids to do workValves are used to control the movement of fluids

Therefore, valves control the location of fluid pressure Check valves only allow fluids to flow in one direction

Hydraulic multiplication allows small changes in pressure to do large amounts of work.

See page 421

A small area applying pressure can cause a large force to be exerted over a large area.

Pressure applied at A5000 N on a 0.5 m2 piston = 10 kPa pressure

Force applied at B10 kPa applied on 5.0 m2 piston = 50 000 N

44

Application of Hydraulic Systems

“Jaws of Life” refers to several types of hydraulic tools like, spreaders, cutters, and rams. These tools are used to manipulate vehicles that are involved in accidents.

Rams: Liquid is injected into a cylinder forcing the piston to “ram” against the car frame

45

Problems in Hydraulic Systems

Hydraulic systems must be designed carefully Minimize twists and turns to allow fluid to flow freely Connect pipes and seams well to avoid leakage Pressure in the system is affected by the size of the pipes

and the smoothness of the inside of the pipes. Pressures can be dangerous if fluids allowed to escape

through broken pipes or lines. Pressure-relief valves re often used to control pressures

Fluids are often poisonous

See page 32946

Pneumatic Systems

Pneumatic systems use a gas under pressure Same idea as hydraulics, except gases can be compressed,

whereas fluids do not compress much. Compressors are used in pneumatic systems, not pumps

Compressors build up pressure, then quickly release it in a small area to produce large forces

Pneumatics can be used in large and small systems Pneumatics and hydraulics are often used together

See pages 330 - 33147

Pneumatic Systems and their Problems

Pneumatic systems must have unblocked air flow to work efficiently.

Because air is usually brought into a compressor to increase pressure, filters clean the air to keep the compressor clean

If the filters are not cleaned, the pneumatic system become inefficient

See pages 330 - 331

Take the Section 9.2 Quiz

What did we do before email attachments and faxes? This Rohrpoststation used pneumatics to “shoot” tubes with rolled up documents around large building like factories. If the station’s compressor filter was blocked, important messages could become lost.

48

9.3 Natural Fluid Systems

Many natural systems are based on fluids and pressures Weather systems are created and influenced by barometric

pressure, measured with a barometer. Air pressure is measured in kilopascals (kPa)

or atmospheres (atm) Humans are affected by air pressures (breathing)

and fluid pressures (the circulatory and respiratory systems) Water, and water balance, is vital for life The human body is 66% water, and

loses 2.1 L of water daily

See pages 334 - 33549

The Circulatory System

The circulatory system is one of the most complex hydraulic systems we know The heart is the pump, and blood vessels are specialized

pipes Blood pressure refers to how hard blood pushes against the

walls of your body’s blood vessels Nerve cells in the arteries monitor blood pressure• Your pulse is these waves of pressure• Normal resting heart rate is 60 - 100 beats per minute• Blood pressure is measured with a sphygmomanometer

which measures two different pressures Eg. Blood pressure = 120/75 mm Hg = two pressures 120 = heart pumping, and 75 = heart relaxing and filling with blood See page 336

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Disorders of Blood Circulation

Blood pressure is a part of normal check-ups, as it is an indicator of overall health

Like in all hydraulic systems, roughness inside of pipes decreases the hydraulic system’s effectiveness

Fatty deposits build up in arteries to slow blood flow

Smoking and obesity also increase blood pressure

See page 337www.nhlbi.nih.gov 51

The Respiratory System

Breathing is partly based on air pressure changes Air (and all fluids) normally move from high to low pressure INHALING: Diaphragm and rib muscles expand the rib cage,

increasing volume and decreasing pressure The diaphragm and rib muscles expand your lungs Air from outside, which has oxygen in it, enters the low

pressure in the lungs EXHALING: is the diaphragm and rib

muscles pushing inwards, increasing pressure in the lungs so air leaves As the air leaves, it takes

unwanted carbon dioxide See page 338

52

Disorders of Breathing

Breathing is affected by narrowed passageways, especially swelling from infections and allergies Smoke, polluted air, coal dust and asbestos are also harmful Asthma is a respiratory disease that narrows the

passageways for air entering and leaving the lungs Asthma can be triggered by smoke and pollutants,

exercise, stress and dust An inhaler is used to deliver tiny droplets of medicine to

the lungs to help passageways open

See page 339

Take the Section 9.3 Quiz53

Chapter Review H.W. Pg# 344-345#1, 4-8, 10

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