Unit 3 Fluids & Dynamics

1. Unit 3Fluids & Dynamics Chapter 7 -- Kinetic Molecular Theory Chapter 8 --Fluids are affected by forces, pressure, and heat Chapter 9 -- Natural and Constructed fluid systems

2. Chapter 7 Mix and Flow of Matter

3. 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). Comparing the basketball and bowling ball, which has more mass? Volume? See pages 246 - 247

4. 7.1 States of Matter The four familiar states (phases) of matter. plasma solid gas liquid See pages 246 - 247

5. 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 248

6. 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. As the rollercoaster’s speed increases, its kinetic energy also increases. See page 249

7. The Kinetic Molecular Theory The main points of the kinetic molecular theory include: All matter is made of very small particles. There is empty space between particles. Particles are constantly moving. The particles arecolliding with each other and the walls of their container. Energy makes particles move. The more energy theparticles 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. See page 249

8. HomeworkPg# 249 #1-5

9. 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. Can you use the concepts of thermal expansion and contraction to explain how a thermometer works? See page 250

10. 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 251

11. Changes of State • Melting point is the temperature at which solid turns to liquid. • Boiling point is the temperature at which liquid turns into gas. See pages 252 - 253

12. Changes of State Solid Melting Liquid Boiling Gas See pages 252 - 253 Take the Section 7.1 Quiz

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

14. 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. 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. See page 261

15. Layers of Fluids Fluids that do not mix, layer themselves according to their density. Less dense fluids “float” on top of more dense fluids. oil Can you list the objects, in this beaker, from most dense to least dense? ball water See pages 262 - 263

16. Measuring Density

17. Measuring Density 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 See page 264

18. Calculating Density 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 page 265 See next slide for the answers.

19. Calculating Density 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 See page 265 Take the Section 7.2 Quiz

20. HomeworkPg# 272 + 273Checking Concepts#1-8, 13-15

21. 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. 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. See page 276

22. 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 Tension force during a game of “tug-a-war” See pages 277 - 278

23. 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 g m= mass g= Gravitational Constant; 9.8m/s on Earth See page 279

24. Weight Depends on Gravity • 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. See page 280

25. Measuring Force 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 See pages 282 - 283

26. 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 - 285 Take the Section 8.1 Quiz

27. 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. The tennis racket applies a force to the ball. The resulting pressure causes the ball to compress. See page 290

28. 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. Explosion L.P. H.P. Implosion L.P. H.P. See page 291 - 292

29. Liquids and Solids Are Very Difficult to Compress The 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. When force is applied to the bottle, the liquid does not compress. There is no room for the liquid particles to move closer together 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 A bottle filled with gas See page 293

30. Compression and Deformation 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. See pages 293 - 294

31. 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 kPa Air pressure can be measured using a simple wet barometer as shown. See page 295

32. 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. Go to the next slide to check your answers See page 296

33. 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) Since the clown’s weight is spread out over many nails, the pressure at each nail is small. See page 296 Take the Section 8.2 Quiz

34. 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. Oil has a larger viscosity than water, therefore oil has a slower flow rate. See pages 300 - 301

35. 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 Temperature effects how easily a liquid pours. See page 302

36. 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. The water’s surface tension allows this insect to remain supported. See pages 304 - 305 Take the Section 8.3 Quiz

37. 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 - 316

38. 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! • This same idea is used for many purposes, including hydraulics, water rockets and dental tools. See page 316

39. 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 317

40. Rising and Sinking • 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 See page 318 Take the Section 9.1 Quiz

41. 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. By using pumps and levees, New Orleans is usually kept dry. When Hurricane Katrina overwhelmed their fluid-control systems, however, tragedy occurred. See page 324

42. 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 Air moving faster over the wing creates higher pressure underneath = lift force See pages 325 - 326

43. 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 A pump (top) first creates low pressure to draw water in, then high pressure to pump it out. See pages 326 - 327 Low P High P

44. Valves and Hydraulic Multiplication Hydraulics = using pressure in Liquids to do work Valves 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. • A small area applying pressure can cause a large force to be exerted over a large area. Pressure applied at A 5000 N on a 0.5 m2 piston = 10 kPa pressure Force applied at B 10 kPa applied on 5.0 m2 piston = 50 000 N See page 421

45. 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

46. 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 329

47. 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 - 331

48. 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 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. See pages 330 - 331 Take the Section 9.2 Quiz

49. 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 - 335

50. 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