1. POWERPOINT SLIDESHOW Grade 8 Science MIX & FLOW OFMATTER FLUID DYNAMICS Supporting Science Textbook Content while enriching the Learning Process in Junior High/Middle School

2. FLUID DYNAMICS Concept Map Shows the concepts covered within the framework of this unit Mix and Flow ofMatter Grade 8

3. FLUID DYNAMICS Slides Key Concepts 4 W.H.M.I.S. SAFETY IN THE SCIENCE LAB 5Fluids in Our World - What are fluids? 6 - 7 Fluid Technological Devices - Transporting, Processing, Using 8 - 12 Properties of Fluids - Viscosity, Density, Buoyancy, Compressibility 13The Particle Model 14Temperature & The Particle Model 15Matter – Changes of State 16Classification of Matter 17 - 24 Properties of Mixtures & Fluids - Solutions, Concentration, Solubility 25The Particle Model 26 - 32 Properties of Gases & Liquids - Viscosity, Density, Temperature, Buoyancy, Compressibility 33Pascal’s Law 34 - 40 Fluid Technologies - Solubility, Pumps and Valves 41 - 44 Submarines 45Hydraulics and Pneumatics

4. Working with Fluids - Safely WHMISSAFETY WHMIS symbols - SAFETY in the Science Lab SAFETY PowerPoint Access the SAFETY PowerPoint to review the Concepts It is available by clicking on the image. You can also access Practice Safety Tests online You can also access Practice Safety Tests online @ http://www.edquest.ca

5. Fluids in Our World What are FLUIDS? fluid A fluid - usually a liquid or a gas - is anything that has no fixed shape, resists deformation and can flow (take on the shape of their containers). Liquids form a free surface (a surface not created by their container) while gases do not. The distinction between solids and fluids is not so easy. It is usually made by examining the viscosity of the matter. Pascal's law An important application of a fluid’s resistance to stress applied to it is Pascal's law, which explores the effect of pressure on a fluid's state.

6. Fluids in Technological Devices TRANSPORTING FLUIDS Fluids help to move solid materials. slurry A mixture of water and a solid is called a slurry. The transportation of solids in water, called slurry technology slurry technology, has many important applications. Forest fires are fought using a fire retardant slurry to help put out the fire. conveyor belts slurry pipeline The mining of Alberta’s Tar Sands provides a good example of how slurry technology has helped industry. Originally, conveyor belts were used to transport the oil sands from the mine to the processing plant. Slurry technology made this type of material movement less expensive through the use of a slurry pipeline – pumping the oil sands from the mine to the processing plant.

7. Fluids in Technological Devices PROCESSING FLUIDS Fluids take the shape of the container that holds them. Many solid materials are originally prepared as liquids. Glass, steelconcrete Glass, steel and concrete are examples of solids that were originally prepared as liquids to shape them easier. When they cooled, or dried, as a solid they are in the form, or shape they need to be in to serve their purpose. Froth flotation Froth flotation is a method used to process minerals by separation using surfactants and wetting agents. This separation method makes processing complex (mixed) ores economically feasible. MATERIALS USING FLUIDS Fluids flow and as they do, they carry other materials along with them. Toothpaste‘binder’ Toothpaste is an example of such a fluid. It has A ‘binder’ (made from wood pulp) that keeps all of the ingredients that make up toothpaste together as it flows out of the tube and onto your toothbrush.

8. Properties of Fluids VISCOSITY Viscosity Viscosity is a measure of the resistance of a fluid to flow. Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. It is commonly thought of as "thickness”. Soda pop is "thin", Corn syrup is "thick" with a low viscosity, having a high viscosity. Measuring Viscosity ramp method Viscosity can be easily measured using the ramp method. Pour different liquids down a ramp and time how long it takes for each of them to get to the bottom. The one that is the slowest will be the most viscous.Reminder: Increasing temperature lowers viscosity (makes it thinner) Decreasing temperature increases viscosity (making it thicker)

9. Properties of Fluids TEMPERATURE and VISCOSITY syrup When thick syrup is poured over hot pancakes, the syrup becomes thinner and runs over the sides of the pancakes. motor oil When thick motor oil is added to the engine of a car, the oil thins out when the engine heats up. Olive oil Olive oil is very thin (almost watery). To make it a little thicker it can be placed in the fridge, where it's viscosity can be increased. Asphalt Asphalt (road paving) materials are heated up (making them less viscous) so they can be poured easily before it hardens.

10. Properties of Fluids Density Density is the amount of matter in a given volume. Every substance has a different density, because each substance is made up of different particles. The density of a substance depends on the particles it is made up of. When we talk about density, it's usually mass density we're referring to. The mass density of an object is simply it's mass divided by it's volume. Density depends on whether the object is solid, filled with air pockets, or something in between. Substances that have a higher density than the density of the substance it is placed in will sink, substances that have a lower density than the density of the substance it is placed in will float. CALCULATING DENSITY density (d) = Mass (M) Volume (V) (Memory Method) M dV This simple equation will help you figure out how to solve density problems dV Simply cover up whichever value you need to calculate and the other two are shown in their proper placement, be it to multiply or to divide. For example: cover up the M. This leaves you with d/V Density times volume will give you mass. You can also check it out by way of the units: (g / cm 3 ) x cm 3 cancels out the volume unit leaving grams, the desired unit for mass.

11. Properties of Fluids CALCULATING DENSITY irregular object One way to determine the volume of an irregular object is to measure its mass in air and then in water, subtract the second measurement from the first, and divide by the density of water. Another way to determine the volume of an irregularly shaped object is to submerge the object in a full container of water. The volume of the object equals the volume of water that overflows. Ships can float because they contain a large volume of air. The overall density of the ship is less dense than water, so it floats.

12. Properties of Fluids Buoyancy is the upward force on an object, against the force of gravity, produced by the surrounding fluid in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object. The net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body, enabling objects to float or at least to seem lighter. Buoyancy is important for boats, ships, hot air balloons, and airships. Compressibility Compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure change.

13. The Particle Model of Matter Particle Model of Matter The Particle Model of Matter is a scientific description of the tiny particles that make up all things. All substances are made of tiny particles. All particles in a pure substance are the same. (Different pure substances are made of different particles). All the particles have spaces between them. All the particles are always in motion (the speed of the particles increases/decreases when the temperature increases/decreases). The particles in a substance are attracted to one another (the strength of the attraction depends on the type of particle).

14. Temperature & The Particle Model Temperature Temperature indicates the average energy (speed) of the particles in motion in a substance. increasefaster lostslower An increase in heat makes the particles of a substance move faster. When heat is lost from a substance, the particles move slower. When two substances with different particles are mixed together, the smaller particles of one substance fill the spaces between the larger particles of the other substance. solutesolventdissolving When particles of a solute are attracted to particles of a solvent, dissolving occurs. The solute dissolves in the solvent.Dissolving ‘Universal Solvent’ Water is called the ‘Universal Solvent’ because it can dissolve so many materials. 97% of the water on Earth is Ocean water, 2% is frozen and only about 0.5% is 'usable' (and even this has materials already dissolved in it that can be harmful). The Rate of Dissolving The Rate of Dissolving The speed at which the solute dissolves in a solvent is called the rate of dissolving and can be affected by: - agitation (stirring or shaking) - temperature - surface area of the solute exposed to the solvent

15. Matter - Changes of State change of state A change of state occurs when the particles of a substance gain or lose energy. plasma The most common form of matter in our universe exists in a fluid state called plasma, which is a gaslike mixture of positively and negatively charged particles. (often considered to be the fourth state of matter) - Plasma, if controlled, could be used as rocket fuel. Morphing Morphing is a special film effect that mimics the changes we see in the states of matter. Terminator 2 (like in the movie Terminator 2 - when the policeman morphs into a liquid form)

16. Properties of Mixtures and Fluids CLASSIFICATION OF MATTER

17. Properties of Mixtures and Fluids PURE SUBSTANCES – ELEMENTS & COMPOUNDS All pure substances have their own unique set of properties, or characteristics. Examples include diamond, gold, hydrogen, oxygen and mercury, just to name a few.Elements An element is a chemical substance that is made up of a particular kind of atoms and cannot be broken down or transformed by a chemical reaction into a different element.Compounds compound Two or more elements combined into one substance, through a chemical reaction, is called a chemical compound. A pure chemical compound is a chemical substance that is composed of a particular set of molecules. A common example of a chemical compound is pure water it has the same properties and the same ratio of hydrogen to oxygen. Other common compounds considered to be pure substances include: salt, sugar, aspirin,

18. Properties of Mixtures and Fluids MIXTURES All mixtures contain two or more pure substances, which have their own distinct properties (some of which may be hidden). Homogenous Mixtures solution Homogenous Mixtures – These are mixtures which look as though they have only one set of properties. The blended mixture has equal amounts of both substances (all parts of the mixture are the same). If the homogenous mixture does not have any settling of any of the substances it is made of, then it is called a solution. Solutions occur because each particle slips between each other particle and is evenly distributed throughout the entire mixture. Heterogenous Mixtures Heterogenous Mixtures - If there are two or more materials that are visible within a mixture, then it is called a heterogeneous mixture. The properties of the pure substances, in a heterogeneous mixture, are not hidden. In-Between Mixtures suspension colloid emulsion In-Between Mixtures - A heterogeneous mixture, in which the particles settle slowly after mixing, is called a suspension (eg. orange juice). A heterogeneous mixture, in which the particles do not settle at all, is called a colloid (eg. fog). To disperse the particles for a longer period of time, an emulsifying agent (like a protein) is used to form an emulsion (eg. mayonnaise). mechanical mixtures. T phases Mixtures that are obviously two or more substances are called mechanical mixtures. The separate parts of the mechanical mixture are called phases

19. Properties of Mixtures and Fluids SOLUTIONS dissolving solute A solution is formed by mixing two or more materials together in a process called dissolving. Dissolving occurs because of the attracting between the particles (there may be a stronger attraction to the particles of another substance, than to the particles of the same substance) The solute is the substance that dissolves in a solvent. solvent The solvent is the substance that dissolves the solute to form a solution. Soluble Soluble means to be able to be dissolved in a particular solvent. Solutes and solvents can be gases or liquids. Paper Chromatography Paper Chromatography is a scientific technique (test) that helps to determine if a particular substance is pure or a solution. The procedure enables a substance to be separated out at various levels if it is a solution. If it remains at only one level or color then it is pure.

20. Properties of Mixtures and Fluids Separating Mixtures When fluids are used to make solids flow, the solids must later be recovered. Separation methods are designed to take advantage of the unique properties of the substances that have been mixed. Desalinating Water The ‘desert tent’ method (much like distillation) is inexpensive, but slow, and only practical in areas which receive a lot of Desalination plants bright sunlight. Desalination plants, along the Red Sea, use lots of energy and are very expensive to operate. All seawater contains salt, but in varying amounts - from place to place, with the Dead Sea having the highest concentration. dehydrationsolvent The process of removing water from a solution is called dehydration. The solvent (which is the water, in most cases) is separated from the solution by means of evaporation. Distillation liquid fractions Distillation is a separation method that allows all the liquid fractions of a mixture to be separated from each other and then collected independently.

21. Properties of Mixtures and Fluids Separating Mixtures Processing Petroleum fractional distillation. W vaporize recondense Petroleum is a natural mixture of hydrocarbons and must be processed to recover useful petroleum products. The process that does this is called fractional distillation. When the petroleum is heated, it changes into a gas (vaporize), which is collected and cooled, enabling it to change back into a liquid (recondense). The recondensed liquid is further separated (the parts recondensing at different temperatures) into each of the fractional parts, that are soluble in each other, but not in water. Fractional distillation is done in a two-tower structure and the fractional products can then be converted (further processed) into over 500,000 types of petrochemicals. Mining Mixtures An ore is a mineral (or group of minerals) that contains a valuable substance (like gold). To extract the substance (gold) that needs to be recovered it must be mined and crushed, then mixed with water to create a fine suspension. Chemicals are then added to dissolve only the substance (gold) you want. The substance (gold) is then released from the solution, when another substance (zinc) is added, allowing the residue (gold) to sink and be collected.

22. Properties of Mixtures and Fluids Separating Mixtures Applications Convenience foods are often dehydrated, so they can be stored for long periods of time without spoiling (you just add water when you want to use it). Petrochemical products include aspirin, sports equipment, eyeglasses, chewing gum, duct tape and fertilizer. There are many different types of salt, the most common one is sodium chloride (table salt) – potassium chloride is potash potash. Potash is used in the purification of water, glue spreading, papermaking, painting dyeing, leather producing, fiber board processing and used in rubber production and the fermentation of foodstuffs. sweetwatermaple syrup Sugar beets and sugar cane are refined to give us sugar crystals, maple sap is boiled to make ‘sweetwater’ or maple syrup.

23. Properties of Mixtures and Fluids Concentration Concentration is the measure of how much of a given substance is mixed with another substance. This usually applies to homogeneous solutions, where it refers to the amount of solute in a solvent. concentrate To concentrate a solution, add more solute, or reduce the amount of solvent. dilute To dilute a solution, add more solvent, or reduce the amount of solute. solubility. The limit to concentration is called solubility.

24. Properties of Mixtures and Fluids SOLUBILITY solubility The limit to concentration is called solubility. saturated solution A saturated solution is one in which no more solute will dissolve in a specific amount of solvent at a specific temperature. unsaturated solution An unsaturated solution is one in which more solute can be dissolved in a specific solvent at a specific temperature. Using the particle theory, the attractive forces between the particles becomes balanced and no more particles of the solute can be attracted by the particles of the solvent. super-saturated solution A solution that contains more solute than would normally dissolve at a certain temperature is called a super-saturated solution.

25. GASLIQUIDSOLID assumes the shape and volume of its container takes the shape of the part of the container which it occupies retains a fixed volume and shape particles can move past one another particles can move/slide past one another rigid - particles vibrating in place compressiblenot easily compressible lots of free space between particles little free space between particles flow easily past each other, move in all directions, do not flow to the lowest possible level can be poured (always flowing to the lowest possible level) and form a level (flat) surface at rest form a pile when they are poured (the particles do not continue to flow apart from each other) The Particle Model of Matter

26. Properties of Gases and Liquids Viscosity Viscosity is a fluid’s resistance to flow Fluids can flow. How quickly they can flow is called flow rate. A substance's resistance to flow (how thick or thin it is), or viscosity, affects flow rate. The internal resistance or friction between the particles of the substance determines the viscosity of that substance. The more friction - the more viscous (thicker) a substance is. The higher the viscosity of a substance, the slower it flows. Examples: KetchupPop High ViscosityLow Viscosity ThickThin Viscosity Viscosity changes with temperature - an increase in temperature decreases viscosity.

27. Properties of Gases and Liquids Density Density is the amount of mass in a given volume float Objects that are less dense than 1g/ml float in water. The Dead Sea is one of the saltiest bodies of water on the Earth. When salt is added to water, there are more particles in a given volume, which increases the density of the water, allowing denser objects to float in the saltwater. Temperature and Density Density Density does not change as long as the temperature remains the same. The particle model of matter states that for every substance, the number of particles in a given volume, remain constant if the temperature is kept constant. As energy is added, the particles move more quickly and further apart, thus increasing the substance's volume. When this happens, the density of the substance (which is the mass to volume ratio) decreases because the mass remains constant, but the volume increases. One substance can have different densities, depending on the state it is in.

28. Properties of Gases and Liquids BUOYANT FORCE Buoyancy buoyant force Buoyancy is the tendency of a substance to float. Buoyant objects take up space in a fluid, pushing some of the fluid away or displacing it, causing them to float. This happens because the fluid pushes back against the force of gravity. Less dense objects float on more dense substances because of buoyant force. When an object is in a liquid, the force of gravity pulls it down. The liquid itself has a force that acts against the force of gravity. This buoyant force pushes objects upward. negative buoyancy positive buoyancy neutral buoyancy Objects that are more dense than water sink (negative buoyancy); objects that are less dense than water float (positive buoyancy); objects with the same density as water hover (neutral buoyancy) - they are suspended - neither sinking nor floating. ForceNewtons Force is a push or a pull on an object - measured in Newtons (N). The upward force of a fluid on an object is called its buoyant force, which is also measured in Newtons. Calculation of Buoyant Force Buoyant Force = Weight in Air - Weight in Liquid

29. Properties of Gases and Liquids BUOYANCY APPLICATIONS Buoyancy has important applications in transportation. Ships are designed to float in all types of water, regardless of the density of the water. Plimsoll Line This is possible because of the Plimsoll Line - which shows how heavily a ship can be loaded in different water conditions. fresh water saltwater The marks on the left indicate fresh water The marks on the right are for saltwater.

30. Properties of Gases and Liquids BUOYANCY APPLICATIONS Hot Air Balloons Hot Air Balloons - As the air inside the balloon is heated, it becomes less dense than the surrounding air. The buoyant force of the air will push the hot air balloon upwards, until the buoyant force equals the force of gravity. Learn about zeppelins HINDENBERG -like the HINDENBERG

31. Properties of Gases and Liquids COMPRESSIBILITY compression When a force acts on a fluid, that fluid is under compression. Some fluids under compression will take up a much smaller volume compressible – these fluids (like most gases) are compressible. Other fluids (like most liquids) will have almost the same volume incompressible – making them incompressible. In terms of the particle model (the spaces between the particles), it explains why there is such a difference in compressibility between gases and liquids. When a force is applied to the particles, much more compression takes place in a gas.

32. Properties of Gases and Liquids Pressure Pressure is the amount of force applied in a given area. pascals It is measured in pascals (Pa) 1 pascal (Pa) equals a force of 1 Newton (N) over a given area of 1m2 1Pa = 1N 1m 2 The more force applied to a given area, the greater the pressure. PRESSURE CALCULATIONS P = F The formula to calculate pressure is P = F F A A PA shortcut The ‘ shortcut ’ formula is: Remember: cover the unknown part of the formula to determine what you have to do. Most measurements of pressure are in kilopascals (kPa) Note: 1kPa = 1000 Pa Pressure can also be measure in N/cm 2

33. Properties of Gases and Liquids PASCAL’S LAW In the mid 1600’s Blaise Pascal studied and experimented with enclosed fluids. Through his experiments, he found out that the force applied in a closed fluid system created pressure that was transmitted equally in all directions throughout the fluid. an enclosed fluid transmits pressure equally in all directions Pascal’s Law states that an enclosed fluid transmits pressure equally in all directions This law has very important applications. Water flows out of a container in the way Pascal’s Law illustrated here, because of Pascal’s Law. The pressure of the water on the sides of the bottle is equal at the same depth, because the water travels the same distance outward before landing. The Greater the Depth, The Greater the Pressure - The Greater the Depth, The Greater the Pressure - Pressure increases with depth. The more water above the hole, the greater the pressure and the further the water will shoot out of the hole.

34. Fluid Technologies BASED ON SOLUBILITY "hydrophobic" Fat & dirt are, "hydrophobic" (meaning "afraid of water"). Hydrophobic materials do not solve in water. surfactant A detergent is a substance that can remove dirt from fabrics. Most detergents are liquids or powders that are soluble in water. They contain a cleaning agent called a surfactant. emulsion How does a surfactant work? Almost all surfactants are long chain chemicals that have a polar end (water- loving or hydrophilic) and nonpolar end (water-hating or hydrophobic). The nonpolar end is attracted to grease, oil and dirt (the hydrophobe) while the polar end is attracted to water. Soap (the surfactant) encapsulates the fat & dirt molecules in the water, removing them from the fabric. In this way the dirt and water forms an emulsion, which can then be drained away. Phosphates were once used in detergents, but the environmental side effects were bad. Because phosphates encourage plant growth, the phosphates would cause weeds to overgrow in water systems and choke out the sunlight.

35. Fluid Technologies DETERGENT INGREDIENTS IngredientFunctionIngredientFunction surfactantcleans fabricbuildersoftens water fillerprevents clumping corrosion inhibitor prevents rusting suspension agent prevents reattachmentenzyme removes protein stains bleachremoves stainsoptical whiteneradds brightness fragranceadds scentcolouring agent gives detergent colour

36. Fluid Technologies DRY CLEANING Dry cleaning was invented accidentally in 1855. A kerosene lamp was spilled on a table cloth and later cleaned. The tablecloth seemed to be much cleaner, so the ‘dry cleaning’ process was born. perchlorethylene – PERC Early solvents used, such as gasoline, kerosene, carbon tetrachloride and trichlorethylene, had some success in cleaning clothes, but the disadvantages to the safety of those using the solvent and to the environment, led to the development of a synthetic solvent named perchlorethylene – PERC. The dry cleaning process is also very efficient – the washer and dryer are all together in the same machine, and almost all of the PERC can be recovered and reused over and over again.

37. Fluid Technologies DIVING DECOMPRESSION S.C.U.B.A.Self- Contained Underwater Breathing Apparatus Going below the surface of the water is now possible because of the S.C.U.B.A. (Self- Contained Underwater Breathing Apparatus) gear (air tanks and regulators) that were invented to help a diver breath underwater. When going deeper, nitrogen can dissolve in the divers body cells and tissues in a higher concentration than normal. As the diver rises slowly back to the surface, the nitrogen will leave the body gradually. If the diver ascends too quickly the nitrogen gas bubbles out of the blood and tissue, or collects in different parts of the body causing extreme pain. “bends”hyperbaric chamber The “bends” can be treated in a hyperbaric chamber, which forces the nitrogen to re-dissolve back into the blood and tissue.

38. Fluid Technologies PUMPS Glossary of Pumps Visit: Glossary of Pumps... a fantastic resource for this Topic. http://www.animatedsoftware.com/pumpglos/pumpglos.htm pump To obtain water from below the surface (the groundwater) and to move a fluid through a fluid system, you need to use something that will work against the pull of gravity, a pump. Archimedes Screw One of the first pumps invented was Archimedes Screw (invented to remove water from the hold of a ship). Pumps in a city are used to move water to an elevated reservoir (so the force of gravity can allow the water to flow into all the homes - you see this in a small town as well - a water tower is usually the tallest structure in this town). Pumps are also use to move oil, natural gas and other fluids through pipelines. Pumps are located in automobiles to get the gasoline from the fuel tank to the engine. Pumps are also use to force air into tires. Your mouth is also a pump that can be used to draw a fluid up a straw and into your mouth.

39. Fluid Technologies VALVES regulate the flow of a fluid Valves are devices that regulate the flow of a fluid. flowratevolumepressure direction Today's valves can control not only the flow, but the rate, the volume, the pressure or the direction of liquids, gases, slurries or dry materials through a pipeline, chute or similar passageway. A Valve is a product rarely noticed by the average person, yet it plays an important role in the quality of our lives. It is essential to virtually all manufacturing processes and every energy production and supply system. Yet it is one of the oldest products known to man, with a history of thousands of years. Each time you turn on a water faucet, use your dishwasher, turn on a gas range, or step on the accelerator of your car, you operate a valve. Without modern valve systems, there would be no fresh pure water or automatic heat in your home. There would be no public utilities, and beyond wood and coal, almost no energy of any kind. Plastics would be unheard of, as would many inexpensive consumer products.

40. Fluid Technologies VALVES Valves Valves can:... turn on and turn off, regulate, modulate or isolate.... control flow of all types, from the thinnest gas to highly corrosive chemicals, superheated steam, abrasive slurries, toxic gases and radio active materials.... handle temperatures from cryogenic region to molten metal, and pressures from high vacuum to thousands of pounds per square inch.... range in size from a fraction of an inch to as large as 30 feet in diameter... vary in complexity from a simple brass valve available at the local hardware store to a precision-designed, highly sophisticated coolant system control valve, made of an exotic metal alloy, in a nuclear reactor.

41. Fluid Technologies SUBMARINES Submarines are designed for use at great depths. Their rigid, double-walled hulls allow the crew to live and work normally underwater for as long as air and power supplies last. Submarines are steered by turning a rudder left and right. A propeller moves the sub through the water--pushing against the water and creating a forward force. How Submarines Work ballast tanks Inside a submarine there are containers called ballast tanks. If these are full of air, the submarine will float. Even though it is made of steel, the average density of the submarine is less than that of water. By pumping water into the ballast tanks, the submarine can sink. This is because when its ballast tanks fill with water, the submarine has a greater density than water.

42. Fluid Technologies SUBMARINES – The Details An object floats if it displaces enough water to support its weight. Subs don't sink because their metal shell (or "hull") surrounds a volume weighing less than an equal amount of water. Subs can sink, rise, and float underwater (maintain "neutral buoyancy"). When the ballast tanks are full of air, the sub weighs less than the volume of water it displaces (is less dense than water) and it floats. When the ballast tanks are flooded with water, the sub weighs more than the water it displaces (is more dense than water), and it sinks. To rise again, the sub reduces its density by pushing compressed air into the ballast tanks. The air forces the sea water out, and the sub goes up toward the surface. To move beneath the surface and to hover, the amount of water in a submarine's ballast tanks is made equal to the weight of the water it is displacing.

43. Fluid Technologies SUBMERSIBLES submersible A deep-diving submarine used to explore the ocean is called a submersible. Submersibles are usually smaller than submarines. They are often equipped with external cameras, manipulating arms, and special lights. Submersibles are built to do specific jobs. They are used to help us recover "black box" flight recorders from wrecked airplanes, bury cables in the sea floor, investigate ancient shipwrecks, map the ocean floor, look for signs of undersea earthquakes, study marine life, repair damaged offshore oil wells, take rock samples of the ocean floor, and study ocean currents.

44. Fluid Technologies BATHYSCAPHS, ROV’s (Remotely Operated Vehicles) & SUBMERSIBLES Trieste Trieste, went 11km beneath the surface to the bottom of the ocean in 1960. Kaiko Kaiko, a Japanese ROV can dive over 11 kilometres. Mariana Trench In 1994, Kaiko went down to the Mariana Trench, the deepest spot in the ocean! Serafina Serafina the world’s smallest remote controlled submarine is only 40 centimeters long! It can go down 5000 metres and perform many scientific tasks. Alvin Alvin, is a submersible that was used to recover a hydrogen bomb accidentally dropped from an air force bomber back in 1966. The world’s largest submarines can stretch up to almost 200 metres.

45. Fluid Technologies HYDRAULICS Pascal’s discovery led to hydraulic systems the invention of hydraulic systems. ( This concept is covered more extensively in - Mechanical Systems )PNEUMATICS compressed air Pneumatic devices use compressed air instead of a liquid. (This concept is also covered more extensively in - Mechanical Systems) Automobile - Pneumatic Air Brakes Dental – Pneumatic Drill completely sealed For both of these systems (hydraulics and pneumatics) to work efficiently and effectively, the entire system must be completely sealed. A leak of any kind in the system allows the fluid in the system to escape and pressure will be lost. (even the smallest hole or crack can cause the system to fail)