Science 8

Science 8Unit 2- FluidsBig IdeasFluids are an important component of many systems. Fluids have different properties that determine how they can be used.Fluids are essential to life.Overall Expectations1. analyse how the properties of fluids are used in various technologies, and assess the impact of these technologies on society and the environment; 2. investigate the properties of fluids; 3. demonstrate an understanding of the properties and uses of fluids.What are fluids?If you had to come up with a definition of a fluid, what would it be?FluidsFluids are materials that have no fixed shape and that are free-flowing (take the shape of their container)BOTH liquids and gases are fluids

How does the scientific definition change your idea of what fluids are?Lesson 1- Fluids in the bodyThe majority of your body is made up of fluidsWe have all been hearing for years that we are mostly made up of water (% differs depending on who you talk to)

Other than water, what other fluids do we have in our bodies?Fluids in our bodiesFluidJob within the bodyOxygenHelps us use the energy within our bodiesBloodMoves particles into and out of cellssweatCools us downSalivaBreaks down our food, helps us swallowUrineTakes wastes from bodyStomach acidsBreaks down food for digestionFluid Systems in the bodyOur body has several systems within that help us function every day. Fluids are integral to several of these systems:

1. Circulatory System2. Respiratory System3 .Urinary SystemCirculatory SystemMoves blood through our bodyBlood carries oxygen, co2, nutrients, hormones, etc. Works with the respiratory system to create the cardiovascular systemThe heart pumps to send blood away from the heart to the body through arteries (with oxygen in it) and to the lungs (to receive oxygen)Veins return used blood to the heart to start the process again

Respiratory SystemThe system that brings air into our bodiesWe take in air, use oxygen, and breathe out (mostly) carbon dioxideOnce the air is in our bodies, the respiratory system works with the circulatory system to get the oxygen to our cellsWe inhale through our nose/mouth, the air travels down the trachea (windpipe), into the bronchial tubes and into the lungsAt the end of the bronchioles there are tiny sacs called alveoli, which absorb the oxygen into your blood (then the circulatory system takes over)Our bodies produce carbon dioxide as waste which travels through the respiratory system in the opposite orderThe diaphragm helps in breathing by contracting/pulling down during inhalation and relaxing during exhalation

Urinary SystemAlso known as the renal system, this system rids the body of waste, regulates blood pressure, chemicals in the blood, etc.The kidneys filter waste from the blood and create urineIf your kidneys dont filter waste from the blood properly, a dialysis machine can clean your blood for youThe bladder then stores the urine until it is ready to exit the body

Questions for your notesIs air a fluid? Explain why or why not.Name three fluids that you need in order to live.What do kidneys do? What treatment is needed if kidneys dont work properly?Choose a body fluid. Why is that fluid important to your body? What do you think would happen to your body without that fluid?Lesson 2- Characteristics of FluidsLast class, we learned a definition for fluids. Who remembers what it is?

Fluids..Fluids are materials that have no fixed shape and that are free-flowing

Liquids and gases are both fluids, but that does not mean they are the same. Each state has its own set of properties- some that are shared amongst both liquids and gases, some that are different between the twoShapeAs we discussed earlier, neither liquids or gases have a definite shape; both take the shape of the container they are in.

Even though you cannot see the gas inside these containers, the have taken their containers shape like the liquids- trust me

VolumeLiquids have a definite volumeIf you have 2 L of water, it doesnt matter what container you put it in, the volume will be 2 Lif you took the 2 L of coke in the bottle, and poured it into the 50 L garbage can, it would barely cover the bottom, but there will still be 2 L of cokeGases do not have a definite volumeThink about perfume- If you spray a tiny bit from a bottle (a liquid), it evaporates, becomes a gas, and fills the whole roomAll gases will fill whatever container (or room) they occupy

Why the difference?The particle theory helps explain the similarities and differences between states of matter (solids, liquids, and gases)Particle theory of matterAll matter is made of particlesAll particles have empty spaces between themParticles are constantly moving in random directionsParticles move faster and spread further apart when they are heatedParticles are attracted to one another

SolidsParticles in solids have a strong connection to one another and have less space between them. So, when they move, they only vibrate. They do not slide past one another which is why solids have a definite shape AND volume (and why solids are not fluids

LiquidsIn liquids, the particles are not as strongly attracted. Therefore, there is more space between them.The connection is strong enough to hold liquids together, so they have a definite volumeBUT the connection is weak enough to allow the particles to slide around more freely, which is why liquids do not have a definite shape

GasesIn gases, particles are really far apart because they have a weak force of attractionGas particles go wherever they please (within their containers) which is why they do not have a definite shape or volume

For your notes..Fill out the chart below to show the differences between solids, liquids and gases

Attraction between particlesDefinite shape?Definite volume?SolidLiquidGasFlowAll fluids have the ability to flow

This is a characteristic of fluids

This happens because the particles inside liquids and gases are not strongly attracted to one another to stay put; they can move around (think about what happens when you like a boy or girl. If you really like them, you stay put. But, if your attraction fades, you might start to wonder other places)Examples of how fluids flowWhere does oil flow?Where does air flow?Where does water flow?

If you fill a container full of sand, poke a hole in the top, and tip it over, the sand will flow, right?Does that mean that sand is a fluid?

WRONG!!!The sand isnt actually flowingAll the individual grains of sand are moving through the hole (thanks to gravity) but each gain is keeping its shapeAir, water, and oil particles can flow freely

Types of Flow1. Laminar

Smooth and regularuninterruptedLess energy required2. Turbulent

Choppy and irregularSomething interruptsRequires more energy and moves slower

RapidsThe water flow shown here is an example of turbulent flowWhat has interrupted the flow of this water?Is this good or bad?

GoodTurbulent flow of water is actually great for the environment!It adds oxygen to the water that living things need to surviveIts also a lot of fun for white water rafters and kayakers

Fluids flowing in our bodiesDo we want laminar or turbulent flow of blood in our circulatory system?

Why?

LaminarFree-flowing blood is definitely needed in our veins and arteries to get our blood where it needs to go quicklyIf plaque builds up in our arteries, it can lead to blockages that create turbulence and can cause blood clots, heart attacks, and strokes!

Different types of flowGolf balls have tiny dimples on them that are designed to create turbulent flow of air.

Why?

For your notes..What are the two main characteristics of fluids?What are the 5 parts of the particle theory of matter?Why cant solids flow?Why isnt salt considered a fluid?What are the two types of flow? (with examples)Why are airplane wings designed for laminar flow, not turbulent flow?

Lesson 3- ViscositySome fluids flow very quickly while other flow slowly.

Give an example of eachFast vs. SlowMolasses flows very slowlyWater flows quite quickly

Why dont they both flow the same?Flow rateWe can determine how fast (or slow) fluids move by measuring the volume that a fluid moves past a point in a certain amount of time (like a racer crossing the finish line)

For example, if it takes you 10 seconds to fill up your 5 L Brita container from the tap, the flow rate is :

5 L/ 10 s = 0.5 L/s

If you turn your tap on full blast, it will fill faster Than if you decrease your water flow**What else might affect flow rate?

Factors affecting flow rateThe size of the openingThe force pushing on the fluidThe surface the fluid is flowing overThe type of fluidViscosity

ViscosityThe substances viscosity also affects flow rateViscosity is the substances thickness or resistance to flowGenerally, the thicker the fluid, the slower it flowsThink about table syrup- does it flow faster when you leave it on the counter or keep it in the fridge? Why?

Factors affecting viscosity1. Cohesion

How strongly the particles in the fluid are attracted to one anotherThe stronger the attraction, the slower the flowWeaker attraction = faster flow2. Adhesion

How strongly the particles are attracted to the particles of another substance (often the particles of the container)This is why rivers flow more quickly in the middle than at the edges

Viscosity in NatureThe viscosity of magma can affect the type of volcanic eruption that happens and even how the volcano is formedMagma that is less viscous (flows faster) leads to more eruptions because gas can escape through it easierThese types of eruptions are less violent and lead to lava flows that create gentle sloping sides to volcanosMore viscous (slower flowing) magma leads to less eruptions because gas is trappedHowever, when the explosions happen, they are more violent because of the pressure that builds upLava shoots into the sky and volcanos with steeper slopes are formed (because the lava moves faster)Non-Newtonian FluidsNot all fluids act the same (as I am sure you have already realized)

BUT.would you believe me if I told you that there are fluids out there than can stop bullets and support your weight??

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

http://www.youtube.com/watch?v=3zoTKXXNQIUhttp://www.youtube.com/watch?v=cn0mIj0_4wsFor your notes (Viscosity)It takes Jimmy 5 minutes to fill a 2 L bottle of molasses. Calculate the flow rate of the molasses in L/min.What are the 5 factors that affect flow rate?What are the two factors that affect viscosity?How does viscosity affect volcano formation?Name one non-Newtonian fluid and describe how it is different than regular fluidsFill out the cart below to show your understanding of cohesion vs. adhesion

ExampleCohesion or Adhesion?Your hands are wet after washing dishesThe yolk and the egg white stick together when you pour it into a bowlMotor oil lubricates the parts of the cars engineA paper clip floats on the surface of waterThere is chocolate syrup left in the bottom of your glassViscosity ExperimentNext class, we will test the viscosity of different fluidsLets brainstorm different liquids that you would like to test..Viscosity ExperimentMaterials needed: cardboard, plastic sheet, spoon, various liquids..Procedure: We will time how long it takes each liquid to travel down the cardboard (or plastic sheet) from start to finishFill out the prediction sheet then compare our predictions to our results

FluidProjected RankActual rank (time)Lesson 4- DensityDensity is the measure of the amount of matter per unit volume of a substanceEvery substance has a density that can be calculated/measured

Think about two completely different substances; We would need a lot more Styrofoam to make 1 kg than we would need to make 1 kg of rocks. This is because rocks have a higher density than Styrofoam.

Density depends on two thingsThe mass of the particles(how much matter is in a substance)How tightly packed the particles are

The more tightly packet the particles, the more dense the substance is

Thinking backLast lesson, we looked at the spaces between particles in each state of matter

Because particles in solids are closest together, solids are usually more dense than liquids, and gases (least dense)

Calculating DensityNot all fluids (liquids or gases) have the same density.Think about oil and vinegar salad dressing. The two parts dont mix together even when we shake them. This is (at least partially) because vinegar is more dense. Oil will settle on top (because it is less dense) To calculate the density of a substance, you divide an the mass by the volume.

D = m/v or = m/v ( is the Greek letter rho)

The density of solids and liquids are commonly expressed in g/mL or g/cmGases; kg/mWhy do you think we measure gases in kg but solids and liquids in g?

Densities of common gasesFluidDensity (NTP) kg/mDensity (STP) kg/mOxygen1.331.43Carbon Dioxide1.841.97Air1.211.29Methane0.670.72Natural Gas0.7Helium0.170.18**Density can be affected by temperature and pressureSeveral common substances have their density measured at NTP (normal temperature and pressure) 20CSTP (standard temperature and pressure) 0CSince helium is less dense than air, balloons filled with helium floatThe worlds Densest liquidAt room temperature, (21C), Mercury is the worlds most dense liquid (13600 kg/m)Also know as quicksilver, is the only metal that is liquid at room temperature

The special properties of waterWater is one of the few substances that actually becomes less dense as it changes from a liquid to a solid (1.0 kg/L vs. 0.92 kg/L)

This is why ice floats to the top of your drink

The Dead SeaA salt lake in the Middle East (bordering Jordan, Israel, and Palestine)It is one of the worlds saltiest bodies of waterDensity = 1.24 kg/LRegular salt water is approx. 1.03 kg/LApprox. density of a human is 1.01 kg/LSince humans are less dense than the water of the Dead Sea, you can float in it

Density Simulationfile:///C:/DOCUME~1/athompso/LOCALS~1/Temp/phet-density/density_en.html

Density DemonstrationWe are now going to use graduated cylinders, water, salt, and food colouring to make this happen.

Anyone know how?

Rainbow water demonstrationFor your notes. (Density)1. Density- the measure of the amount of per of a substance2. The two factors that affect density3. How do you calculate density?4. Why do ice cubes float in a glass of water?5. Complete the Solve Density Problems worksheet (p.173-174 of text for a copy, if you lost yours)

Lesson 5- BuoyancyLast lesson, we learned all about density (the amount of matter per unit volume of a substance)

Density helps determine whether substances sink or float, but it is not the only factor

A screw made of steel will easily sink in water but steel boats that weight thousands of tons (and carry much more weight) float in water.

WHY?

BuoyancyThe upward force that a fluid exerts on an object that opposes the weight of an objectAn objects buoyancy determines whether it will sink or float

Factors affecting Buoyancy1. Weight of the object2. Fluid displaced by the object3. shape of the object4. Density of the objectFluid DisplacementWhen we put anything in a fluid (think water), the fluid is displaced (or moved)

Weight of displaced fluid = upward buoyant force

Objects float when they displace an amount of water that is greater than (or equal to) its own weight

Sinking occurs when the amount of water displaced is less than its own weightShape The shape of an object affects the amount of fluid it displaces

Think about a diver vs. a belly flopper;Divers (good ones, anyway) enter the water by displacing very littleThe other guy? Not so much

The screw vs. the shipThe screw is tiny and displaces very little water

The buoyant force acting on the screw is very small, cannot support the weight of the screw

It sinksCargo ships are large and have a hollow shellThey displace a great deal of waterThe buoyant force acting on the ship is large, so it supports the weight of the ship

It floatsDensityThe density of the fluid is also a factor in buoyancyThe denser the fluid, the more buoyancy force, the easier objects float think back to the Dead Sea example)

Do you think a ship will float more easily in the Atlantic Ocean or in Lake Ontario? Why?

Plimsoll LineEngineers need to understand buoyancy to design ships. Most ships have a plimsoll line painted on them to show how high (or low) the ship will float in different water typesThe notches on the left are freshwater, salt water on the right

Buoyancy Testhttp://www.planetseed.com/files/flash/science/lab/liquids/buoy_exp/en/buoyancy.html

For your notes..BuoyancyDefinition of Buoyancy4 factors that affect buoyancyCheck your Understanding questions from page 177 and Will it Sink of Will it Float? activity on page 178Lesson 6- Pneumatics and HydraulicsPneumatics- systems that use compressed fluids (specifically air or other gases) to workHydraulics- systems that used compressed fluids (specifically liquids) to do workExamples of Pneumatic systemsAir brakesSome exercise machinesPressure gaugesBalloonsAir pumpsAir tubes for mail

Examples of Hydraulic systemsCar liftsWater pumpCombustion engine in a car

Parts of a fluid systemPump- forces fluids through the systemConductor- carries fluid through the systemValve- keeps fluids moving in the right direction at the right time or stops it at the right time)Pressure Gauge- measures pressure in the system

For your notes..Fluids under pressureDefine compressionExplain the difference between Pneumatics and Hydraulics (and provide examples of each)Identify each of the 4 main parts of a fluid system and the job of each

THINGS NOT COVERED IN CLASS (USE YOUR BOOKS)Define pressure and give the formula for it (p. 189)Pascals law (p. 191)The effect of pressure, volume, and temperature on fluids (p. 195)Valves (2 examples where they help systems- circulatory system and engines)- (p. 200-202)