SLE 3 - Viscosity, Density, Buoyancy. & Compressibility

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investigate and compare fluids, based on their viscosity and flow rate, and describe the effects of observe the mass and volume of a liquid, and calculate its density using the formula d m/v [Note:

1 investigate and compare fluids, based on their viscosity and flow rate, and describe the effects of observe the mass and volume of a liquid, and calculate its density using the formula d m/v [Note: This describe methods of altering the density of a fluid, and identify and interpret related practical describe pressure as a force per unit area by using the formula p F/A, and describe applications of investigate and compare the compressibility of liquids and gases pressure in fluids and everyday applications the particle model of matter compare densities of materials: and explain differences in the density of solids, liquids and gases, using the density.] outcome does not require students to perform formula manipulations or solve for unknown terms other than temperature change on liquid flow density, buoyancy and compressibility to the particle model of matter 3. Investigate and compare the properties of gases and liquids: and relate variations in their viscosity, & Compressibility SLE 3 - Viscosity, Density, Buoyancy

2 Viscosity - Product Higher Lower Would I still use this product if the viscosity were higher/lower? List some fluid products you use and ask yourself; The viscosity of different products is very important. Viscosity and Products Flow rate - Topic 4 - Flow Rate and Viscosity

one class to complete your conclusion, and create your blog post conclusion 0.

investigation, record your results, and each member will write a concluding blog post sharing their findings with the group.

3 one class to complete your conclusion, and create your blog post conclusion 0. one class to conduct the experiment, record observations, and begin writing your designing your experiment, and doing the pre-lab write up) two classes to do the pre-lab work (including learning any pertinent information, You will have: brand had the best viscosity. you conducted your experiment, a description of your results, and your recommendations on which Once you have designed your experiment and done the pre-lab write-up work, your group will conduct your investigation, record your results, and each member will write a concluding blog post sharing their findings with the group. The post will be one to two paragraphs briefly describing how a a list of variables (including controlled, manipulated, and responding) a procedure for the experiment 0. a hypothesis a question for investigation (related to viscosity and flow rate) list of materials and equipment a plan for data collection ketchup. In your experiment and write up you must include: Your task is to design an experiment which will test the viscosity and flow rates of several brands of viscosity. next assignment is to test a variety of ketchups to determine which is the best brand in terms of You and your group members are food scientists employed by a consumer report magazine. Your Ketchup Problem

4 C Changes n Viscosfty The viscosity of a liquid, decreases as it is heated and increases as it is cooled. The viscosity of a gas increases as it is heated and decreases as it is cooled. Temperature has the opposite effect on the viscosity of gases as on liquids.

Topic 5 - berisity Using everyday words, density can be described as the crowdedness of the particles

In scientific terms, density is the mass per unit volume of a substance States of Matter 1iqud sold

different substances have different sized particles:the size of the particles determines how many

5 Topic 5 - berisity Using everyday words, density can be described as the crowdedness of the particles that make up matter. In scientific terms, density is the mass per unit volume of a substance States of Matter 1iqud sold The particle model can help explain several important points about the density of substances: different substances have different sized particles:the size of the particles determines how many particles can 11fit into a given space the particle model helps us visualize the empty space between particles of matter ull::j E1H the spaces around the particles reduce the density of the substance

6 bensity of Solids, Liquids and Gases How is the density of a substance related to the substances physical state? States of Matter gas liquid Bolid According to the particle model: solids are more dense than liquids and gases liquids are more dense than gases gases have the most space between particles so they are the least dense iy ()( ) solid liquid gas the particles of a substance are the same size, but the spaces between the particles differ depending on the state of matter they are in.

But lighter isn t really the right word to use Helium gas is very light. It is lighter than air. Here are some problems for you to solve!

of gas in imagine three boxes, all the same size.

If you weighed amount,or volume, of air. Another way of than air because it weighs less than the same density than air. Carbon dioxide is more density than air.

Gases all have different densities. Some gases, such as helium, are lighter than air. Others, such as carbon dioxide, are heavier than air.

7 But lighter isn t really the right word to use Helium gas is very light. It is lighter than air. Here are some problems for you to solve! describing helium is to say that it has a lower dense than air, so we say it has a higher the boxes, the one containing carbon dioxide There would be the same volume of gas in imagine three boxes, all the same size. each box, but their different densities would One way of understanding density is to One box is full of air, one is full of helium, and one is full of carbon dioxide. If you weighed amount,or volume, of air. Another way of than air because it weighs less than the same density than air. Carbon dioxide is more density than air. would weigh the most and the one containing helium would weigh the least. here. Scientists say that helium is less dense make them have different weights. Gases all have different densities. Some gases, such as helium, are lighter than air. Others, such as carbon dioxide, are heavier than air. These boxes ofgas all contain the same volume. They are being weighed on scales which measure veiy small amounts. 1. The balloon contains air. Does the box contain helium or carbon dioxide? Could the box contain air? 2. The balloons are exactly the same size. One balloon contains air. What gas might the balloon marked? contain? What is density?

8 79

bensity of Solids, Liquids and Gases Liquids you cant walk on water because your foot pushes the particles of water aside the particles of a liquid move apart

prevent your foot pushing them apart Gases gases are even less dense than liquids when you move through air, you are moving through mostly empty space there are

9 bensity of Solids, Liquids and Gases Liquids you cant walk on water because your foot pushes the particles of water aside the particles of a liquid move apart easily, allowing a dense, solid object, such as your foot, to pass through the liquid The attractive forces between liquid particles are not strong enough to prevent your foot pushing them apart Gases gases are even less dense than liquids when you move through air, you are moving through mostly empty space there are less particles to move out of your way than in liquids Solids Particles in a solid cannot be pushed apart the particles in solids are very strongly attracted to each other J 7.-.,

bensity: How are mass and volume related? To measure the density of a substance, you first need to know how much of the substance occupies a certain space.

Weight is the force of gravity exerted on an object The mass to volume ratio is the relationship between mass and volume expressed as a quantity of the mass

10 bensity: How are mass and volume related? To measure the density of a substance, you first need to know how much of the substance occupies a certain space. Mass is the amount of matter in a substance Volume is a measurement of the amount of space occupied by a substance Mass and weight are not the same thing Weight is the force of gravity exerted on an object The mass to volume ratio is the relationship between mass and volume expressed as a quantity of the mass (m) divided by its volume (V). b (density) m V Basically, density is the amount of matter (mass) in a certain space (volume), or the crowdedness of a substance.

temperature and pressure stay the same, the mass-to tz5g/cm 3 3 2cm bzlog 2 cm3 can be found

11 it does not change. volume ratio, or density, of any pure substance is a constant, which means as long as the temperature and pressure stay the same, the mass-to tz5g/cm 3 3 2cm bzlog 2 cm3 can be found the following way: for example: the density of an object having a mass of 10 g and a volume of V m You can find the density of a substance by calculating the mass-to-volume ratio.

I following mathematkal formula (problem) can be solved to find density.

$Grade 8 \4ix and Flow of Matter compared to the buoyancy of those same objects in$ What does that tell you about the buoyancy (ability to float) of objects in syrup

What does that tell you about the buoyancy (ability to float) of objects in syrup

Calculation: the following fluids and then answer the question below.

12 I following mathematkal formula (problem) can be solved to find density. As with many things in science, we can use math to figure out the density of a fluid. The 14 Copyright &source Development Services, Edmonton Public Schools, Grade 8 \4ix and Flow of Matter compared to the buoyancy of those same objects in water? 2. What does that tell you about the buoyancy (ability to float) of objects in syrup 1. How does the density of water compare to the density of syrup? The density of water is g/mi. The density of syrup is g/ml Statement: Statement: Answer: Answer: Calculation: Calculation: the following fluids and then answer the question below. Use the density formula to help you calculate (figure out) the density of each of up), we can figure out the density (how tightly packed the particles are). As long as we know the mass (how heavy It Is) and the volume (how much space ii takes Densfly equals Mass dmded by Volume V I, Part F: How can we use math to help us in science?..

11 Name: Date: Student Exploration: Density Vocabu1a: density, mass, matter, volume Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1.

Why do you think some things float and some things sink? Gizmo Warm-up 1. In the Gizmo sect an object and drag it onto the scale.

What is the object s mass? 2. Drag the object into the graduated cylinder.

13 11 Name: Date: Student Exploration: Density Vocabu1a: density, mass, matter, volume Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. List three objects that you think would sink in water. 2. List three objects that you think would float in water. 3. Why do you think some things float and some things sink? Gizmo Warm-up 1. In the Gizmo sect an object and drag it onto the scale. Mas is the amount of matte, or stuff, in an object. A. Which object did you choose? B. What unit of measurement is used for mass? C. What is the object s mass? 2. Drag the object into the graduated cylinder. The number above the cylinder gives the volum, the amount of space the object takes up. A. What unit of measurement is used for volume? B. Which object did you choose? C. What is your object s volume? Graduated Cylinder D. Drop the object into the beaker of water. Does it sink or float? C 2007 ExporeLerning. AI rights reserved.

I L... Be sure the liquid in the beaker is Water. Sink or float? Replace all objects on the shelf. ) 2007 ExploreLearning. AU righb reserved. Will it float or sink?

Draw conclusion: Can you use mass and volume to predict whether an object will sink or B. Can you use volume alone to predict whether an object will sink or float? Explain. A.

14 I L... Be sure the liquid in the beaker is Water. Sink or float? Replace all objects on the shelf. ) 2007 ExploreLearning. AU righb reserved. Will it float or sink? Use the Gizmo to test your prediction. 5. Apply: Measure the mass and volume of the toy soldier: Mass Volume float in water? Explain your thinking. 4. Draw conclusion: Can you use mass and volume to predict whether an object will sink or B. Can you use volume alone to predict whether an object will sink or float? Explain. A. Can you use mass alone to predict whether an object will sink or float? Explain. 3. Analyze results: Look at the data in your table. or sinks. Record your results in the table. 2. Experiment: Use the Gizmo to find the mass and volume of each object and whether it floats Rock Penny Chess piece Apple Golf ball Ping pong ball Prediction Result Object Mass Volume (sink or float?) (sink or float?) 1. Predict: Which objects will float in water? Which will sink? Record your predictions below. Question: How do mass and volume affect sinking and floating? Activity A: Get the Gizmo ready:

... Activity B: Calculating densitt Get the Gizmo ready: Replace the objects on the shelves. Be sure the liquid in the beaker is Water.

To find the density of an object, divide its mass by its volume. Density is recorded in units of grams per milliliter (giml).

Then calculate each object s density and record it. Finally, test whether each one sinks or floats in water. Object Density Sink or Float? Chess piece Rock Toy soldier Apple 3.

15 ... Activity B: Calculating densitt Get the Gizmo ready: Replace the objects on the shelves. Be sure the liquid in the beaker is Water. 4A Question: How does density tell you whether an object will sink or float? 1. Calculate: Densi is the amount of mass in a certain volume. To find the density of an object, divide its mass by its volume. Density is recorded in units of grams per milliliter (giml). What is the density of an object if its mass is 100 g and its volume is 50 ml? 2. Record data: In the Gizmo, find mass and volume of the objects listed below. Then calculate each object s density and record it. Finally, test whether each one sinks or floats in water. Object Density Sink or Float? Chess piece Rock Toy soldier Apple 3. Draw conclusion: The density of water is 1.0 g/ml. Look at the data in your table. How can you use the density of an object to predict whether it will sink or float? 4. Apply: In the Gizmo, either Crown I or Crown 2 is solid gold (but not both) Find the density of the gold nugget and of each crown. (Hint: You will probably need a calculator to do this.) Lcwr12 A. Density of the gold nugget: B. Density of Crown 1: C. Density of Crown 2: D. Which crown is pure gold? 2007 EpIorLearnincj AW rights rv d

Egg-speriment Replace all the objects on the shelf. 2007 ExpIoreLearnngAH rights eserd. where objects float within each liquid.) to least dense. Discuss your answer with your teacher and classmates.

16 Egg-speriment Replace all the objects on the shelf ExpIoreLearnngAH rights eserd. where objects float within each liquid.) to least dense. Discuss your answer with your teacher and classmates. (Hint: Compare 4. Challenge yourself: Using the objects in the Gizmo to help you, list the liquids from densest C. Which liquid do you think is the densest? Least dense? Explain. B. In which liquid does the egg sink the fastest? A. In which liquid does the egg float the highest? 3. Extend your thinking: Observe the egg in each liquid again. your reasoning. 2. Draw conclusion: Which liquids are denser than the egg? Which are less dense? Explain Record what you find in the table below. 1. Observe: Use the Gizmo to explore whether the egg sinks or floats in different liquids. Question: How does an object behave in different liquids? Activity C: Get the Gizmo ready: 4

Part 3... Part 2... Both gravity and buoyancy are measured in Newtons (N).

Buoyant forces oppose the force of gravity.

force is the same as the weight of an object, the object will float if the buoyant force is greater than the

17 Part 3... Part 2... Both gravity and buoyancy are measured in Newtons (N). things down to the center of the earth. Buoyancy pushes things up away from earth. Buoyant forces oppose the force of gravity. Gravity pulls if the buoyant force is less than the weight of an object, the object will sink if the buoyant force is the same as the weight of an object, the object will float if the buoyant force is greater than the weight of an object, the object will rise submerged in fluids. Buoyant Force is the upward force acting on objects Buoyancy is the tendency for materials to rise or float in a fluid. BIN Nye on Buoyancy Part 1... Topic 6: Buoyancy

18 the weight across a large enough area. p.61 Find Out Activity - Cartesian biver bemonstration p. 60 Investigation - Build a bensity Tower bemonstration water as long as the design of the object in the water distributes. Water can support objects that have a greater density than

the the Average bensty = total mass total volume Submarines, blimps and fish also rise and descend in

19 Average density: total mass of all substances divided by total volume. Large ships can float based on this principle. the the Average bensty = total mass total volume Submarines, blimps and fish also rise and descend in water based on changes to average density. their SbJs1 Gei% t5lar 1 IJLIS btr V 1I4 (;k 14, gnj ç Neutral buoyancy occurs when gravity equals buoyancy: an is NOT sinking or rising. object

20 object. submerged fluid, but on the weight of the displaced fluid. The buoyant force does not depend on the weight of the lil::4 equals the weight (force of gravity) of the fluid displaced by the Archimedes principle: The buoyant force acting on an object

Vdcabu1ai: Archimedes principle, buoyant force, density, displace, mass, volume, weight Student Exploration: Archimedes Principle Name: Date: B. How much mass can the boat hold without sinking? A. What are the boat s dimensions?

Experiment with different boat dimensions until you create a boat that holds the (Note: In this Gizmo, the mass of the boat itself is insignificant.) 2. Add cubes until the boat sinks.

21 Vdcabu1ai: Archimedes principle, buoyant force, density, displace, mass, volume, weight Student Exploration: Archimedes Principle Name: Date: B. How much mass can the boat hold without sinking? A. What are the boat s dimensions? Width: Length: Height: most cubes without sinking. 3. Click Reset. Experiment with different boat dimensions until you create a boat that holds the (Note: In this Gizmo, the mass of the boat itself is insignificant.) 2. Add cubes until the boat sinks. What mas of cubes causes the boat to sink? What happens? cubes into the rectangular boat. boat are set to 5.0 cm. Drag one of the green 50-g 1. Check that the Width, Length, and Height of the how these forces cause objects to either sink or float. fr In the Archimedes Principle Gizmo, you will see of gravity causes it to start to sink. As the object sinks, When you place an object in liquid, the downward pull Gizmo Warm-up the liquid pushes back up on the object with a force that opposes gravity. Boat b i + 2. A motorboat is a lot heavier than a pebble. Why does the boat float? 1. Why does a small pebble sink in water? Prior Knowledge Questions (Do these BEFORE using the Gizmo.) ;i Explç ning

Question: How does the mass of the boat relate to the amount of displaced liquid? Click Reset.. Be_sure_the_Liquid_density_is_set_to_1.0_g/mL. Displaced liquid Set the Width, Length, and Height to 5.

Use this information to fill in the last column of your data table. If the liquid s density is I gram per milliliter (the density of water), the mass in grams is equal 5.

22 Question: How does the mass of the boat relate to the amount of displaced liquid? Click Reset.. Be_sure_the_Liquid_density_is_set_to_1.0_g/mL. Displaced liquid Set the Width, Length, and Height to 5.0 cm. umo% the displaced liquid? 6. Draw conclusions: What is the relationship between the mass of the boat and the mass of to the volume in milliliters. Use this information to fill in the last column of your data table. If the liquid s density is I gram per milliliter (the density of water), the mass in grams is equal 5. Calculate: Deisitj is equal to mass per unit volume. To calculate density, divide an object s mass by its volume. (cm) (cm) (cm) (g) liquid (ml) liquid (g) Width Length Height Boat mass Volume of displaced Mass of displaced record the volume of displaced liquid. (If the boat sinks, try a larger set of dimensions.) Record your findings for three boats in the table (include units). Leave the last column blank. 4. Experiment:Click Reset. Choose a new set of boat dimensions. Add cubes to the boat and How much water is displaced into the graduated cylinder? (Units are ml.) 3. Observe: Click Reset. Drag two cubes into the boat, yielding a total mass of 100 grams. 2. Predict: How do you think the mass of the boat will relate to the amount of displaced liquid? The liquid that is pushed into the graduated cylinder is called dipiace4 liquid. 1. Observe: Place several of the 50-g cubes into the boat. What happens to some of the liquid in the tank? Activity A: Get the Gizmo ready:

4. Make a rule: If you know the width, length, and mass of a boat, how can you calculate how and the volume of the boat that is under water? 3.

23 Set the Height of the boat to 10.0 cm. go? How low does it Be sure the Liquid density is set to 1.0 g/ml. : I (Activity B continued on next page) B 6.0cm 5.0cm 150g A 8.0cm 5.0cm bog mass (calculated) (actual) Boat Width Length Boat Sinking depth Sinking depth will sink. Use the Gizmo to check your answers. 5. Practice: Based on what you have learned, calculate how deep each of the following boats deep it will sink in water? 4. Make a rule: If you know the width, length, and mass of a boat, how can you calculate how and the volume of the boat that is under water? 3. Analyze: What is the relationship between a boat s mass, the volume of displaced water, underwater volume of each boat. The units of volume are cm3 and ml (1 cm3 = 1 ml). of the boat that is underwater, multiply the width, length, and depth of the boat. Record the 2. Calculate: Label the last column in your table Volume underwater. To calculate the volume (cm) (cm) mass (g) depth (cm) water (ml) Width Length Boat Sinking Volume of displaced which it sinks, and the volume of displaced liquid. Leave the last column blank. dimensions and loads. In the table, record each boat s width, length, and mass; the depth to 1. periment: Turn on Magnify waterline. Experiment with several different sets of boat Question: How far will a boat sink in water? the mass of displaced liquid. You can use this knowledge to predict how deep a boat will sink. Introduction: In activity A, you learned that, for floating boats, the mass of the boat is equal to Click Reset. i -- Activity B: Get the Gizmo ready: I

B. The volume of displaced liquid: A. How far the boat sinks into the liquid: density of the liquid will change each of the following? 7. Predict: Not all liquids have the same density as water.

24 B. The volume of displaced liquid: A. How far the boat sinks into the liquid: density of the liquid will change each of the following? 7. Predict: Not all liquids have the same density as water. How do you think increasing the imas How far will the boat sink into liquid with a density of 1.2 giml? Check your answer. 12. Practice: A rectangular boat has a width of 5 cm, a length of 8 cm, and a mass of 150 g. 11. Summarize: If you know the length, width, and mass of the boat as well as the density of the liquid, how would you calculate how far the boat sinks into the liquid? the volume of displaced water is equal to the mass of the boat. What is true now? 10. Analyze: In the first part of this activity, you discovered that when a boat is placed in water, 50g 2.Og/mL 50g 0.5g/mL 50g 1.OgImL density depth (cm) liquid (ml) liquid (g) Boat mass Liquid Sinking Volume of displaced Mass of displaced The mass of the displaced liquid is equal to the volume of the liquid multiplied by its density.) Click Reset between each trial. Calculate the volume and mass of displaced liquid. (Note: 9. Gather data: Measure how far the boat sinks into liquids with each density listed below. What do you notice? Move the Liquid density slider back and forth. 8. Observe: Set the Width, Length, and Height of the boat to 5 cm. Add one cube to the boat. C. The mass of displaced liquid: Activity B (continued from previous page)

buoyancy Set the Width, Length, and Height to 10.0 cm. Weight and Click Reset, and turn off Magnify waterline. ilmos (Activity C continued on next page) C.

What happens to the boat when its weight is greater than the buoyant force? 3. Explore: Answer the following questions by dragging the boat up or down in the liquid. D. Why do you think this happens?

25 buoyancy Set the Width, Length, and Height to 10.0 cm. Weight and Click Reset, and turn off Magnify waterline. ilmos (Activity C continued on next page) C. What happens to the boat when its weight is equal to the buoyant force? B. What happens to the boat when its weight is less than the buoyant force? A. What happens to the boat when its weight is greater than the buoyant force? 3. Explore: Answer the following questions by dragging the boat up or down in the liquid. D. Why do you think this happens? C. What happens to the buoyant force when the boat is lifted up? B. Why do you think this happens? A. What happens to the buoyant force when the boat is pulled down? 2. Analyze: Try dragging the boat up or down. Pay attention to the Buoyant force. C. What is the Net force on the boat? A. What is the Boat weight? B. What is the Buoyant force? 1. Observe: Turn on Show data. Place four cubes in the boat. Question: How do gravity and the buoyant force affect a boat? As the boat sinks into the llquid, the liquid pushes back. The force of the liquid pushing up on calculate the weight of a boat, multiply its mass in grams by the boat is called the buoyartforc. down with a force equal to the wei&j! of the boat. Weight is measured in newtons (N). To Introduction: When a boat is placed in liquid, two forces act on the boat. Gravity pulls the boat Activity C: Get the Gizmo ready:

B. What is the mass of the displaced liquid in the graduated cylinder? A. What is the weight of the boat? 4. Observe: Click Reset. Set the Liquid density to 1.0 giml. Add a 50-g cube to the boat.

26 B. What is the mass of the displaced liquid in the graduated cylinder? A. What is the weight of the boat? 4. Observe: Click Reset. Set the Liquid density to 1.0 giml. Add a 50-g cube to the boat. iimos B. Will the ball float or sink? Explain your reasoning. A. What is the buoyant force on the ball? 9. Aly: A hollow ball weighs 40 newtons. In a water tank, it displaces 15 newtons of water. that is equal to the of the displaced liquid. 8 Make a rule Archlmede& principl states that an object is pushed up by a buoyant force 7. Analyze: What do you notice? cubes weight (N) liquid (g) displaced liquid (N) (N) Number of Boat Mass of displaced Weight of Buoyant force liquid in the graduated cylinder, the weight of displaced liquid, and the buoyant force. 6. Collect data: As you add cubes to the boat, record the boat s weight, the mass of displaced displaced liquid? 5. Predict: What do you think is the relationship between the buoyant force and the weight of D. What is the Buoyant force on the boat? (Hint: If the mass is measured in grams, w = m ) C. What is the weight of the displaced liquid? Activity C (continued from previous page)

27 0 The Amazing Egg Hydrometer find out activity page 66 Table 1: Buoyancy of Egg Based on Solution solution water observations salt water sugar water epsom salts sodium bicarbonate

state, but rather on density. density, and will sink lower if the liquid has a lower density.

28 state, but rather on density. density, and will sink lower if the liquid has a lower density. A hydrometer will extend further out of a liquid if the liquid has a higher hydrometer: an instrument designed to measure liquid density. fresh water. more weight per unit volume than together so salt water can support This means the particles are closer density than fresh water. This is because salt water has a higher You saw in the Egg Lab that salt water holds an object better than fresh water. (or float) on something with a higher density This means that something with a lower density will sit on top of The buoyant force of an object does not depend on physical How Buoyancy and bensity are Related

ones that are more dense usually feel heavier. Objects that are Consider: Does density affect buoyancy and, if so, how? Important Information: The density of water is one.

How do you know? 11 Copyright Resource 1)evelopment Services, Edmonton Public Schools, 2003. Giade 8 Mix and llow of Matter prove why your hypothesis was correct. 3.

29 ones that are more dense usually feel heavier. Objects that are Consider: Does density affect buoyancy and, if so, how? Important Information: The density of water is one. When objects are the same size, the 5 small objects that are the same size but have different weights 1. Place each object in the water (one at a time). 1. Which objects had a density greater than water? How do you know? 11 Copyright Resource 1)evelopment Services, Edmonton Public Schools, Giade 8 Mix and llow of Matter prove why your hypothesis was correct. 3. Now, answer the original question using evidence/examples from your investigation OR 2. Which objects had a density less than water? How do you know? Analysis/Conclusion: 2. Record whether each object floats or sinks. 5 clear (glass) containers filled with two cups of water Materials: D objects that are more dense than the fluid they are placed in will float Hypothesis: (check the one you agree with) more dense are made up of more particles packed closer together. D objects that are less dense than the fluid they are placed in will float Procedure/Analysis: (record information in the chart below) Object: Object: Obiect: Density vs. Buoyancy

Consider: How does adding salt to water affect the buoyant force? Important Information: Buoyant force is how hard it pushes up to keep objects floating. Playing with Buoyancy.

30 Consider: How does adding salt to water affect the buoyant force? Important Information: Buoyant force is how hard it pushes up to keep objects floating. Playing with Buoyancy.. (,_ I 1 prove why your hypothesis was correct. Analysis/Conclusion: o Object: I Object: Object: Object: Object: Materials: Procedure: (record information in the chart below) D adding salt to water will increase the buoyant force (make more objects float) D adding salt to water will decrease the buoyant force (make more objects sink) Hypothesis: (check the one you agree with) the salt particles are now taking up extra space in the fluid. Remember what you learned about The Particle Theory of Matter / five small objects used in Investigation 4 clear (glass) container of water I cup of salt (may not need all of it) spoon (or something else to stir with) 1. Mix salt into water one spoonful at a time until no more will dissolve. 2. Repeat procedure from Investigation How did adding salt affect the density of water? How do you know? 2. Now, answer the original question using evidence/examples from your investigation OR Copyright Resource Development Services, Edmonton Public Schools, Grade 8 Mix and Flow of Matter 12

container. The gas must be enclosed in a sealed container with sturdy walls. How can a gas be compressed?? Compression of a Gas kilopascal (kpa) is equal to 1000 Pa. (Pa), after Blaise Pascal.

31 to a unit area. the particles closer together. An external or outside force is applied to the enclosed gas to push apart to behave as a gas. particles are squeezed closer together, they are still far enough There is so much space between particles that even after the Gas molecules distribute themselves equally throughout the container. The gas must be enclosed in a sealed container with sturdy walls. How can a gas be compressed?? Compression of a Gas kilopascal (kpa) is equal to 1000 Pa. (Pa), after Blaise Pascal. The unit of pressure is Newtons/rn 2 also known as Pascals Force is measured in Newtons (N) and area is measured in square meters Cm2). Area (A) A Pressure (P): Force (F) or P Pressure is a measure of the force acting perpendicular Topic 7: Fluid Pressure

Gases are compressible because their particles can be squeezed closer together into a smaller

. When force is applied to a solid or a liquid, the particles cannot move much closer together

The particles themselves do not move in the direction of the force because they have no space

Instead of changing the volume of solids and liquids, an outside force is passed from one

Uses of Compression Gases exert a force back (a counterforce) when they are compressed.

32 Gases are compressible because their particles can be squeezed closer together into a smaller volume. The spaces in liquids and solids are already almost as small as possible.. When force is applied to a solid or a liquid, the particles cannot move much closer together and are incompressible. The particles themselves do not move in the direction of the force because they have no space to move. Instead of changing the volume of solids and liquids, an outside force is passed from one particle to the next, throughout the substance. Uses of Compression Gases exert a force back (a counterforce) when they are compressed. This property can be used to cushion shocks. For example, car tires push back against the force exerted by the car air bags in cars use compressed nitrogen gas to protect a driver in a collision. II tho *rn,,,t In WatIoa in ollinn dnti When y.wr compeler rn.nhnn, an dr bag In,rtlnwz4.0 boo wont bang your bead in tnttcflaiioo.

33 empty juice can scal elastic band Lsoda straws erury A Scare latex balloon Barometer - Barometers are used to measure air pressure. Measuring Air Pressure J ;JfEH retjr I inside and out. Air pressure is hardly noticed. Earths atmosphere is in balance with your body, both the weight of the air on us all the time? Air has mass. If that is the case, then why do we not feel Atmospheric Pressure

34 earth produces air pressure. If you live high up above sea leve slightly. The weight of this air pressing down all around the from an area oflowpressure. high pressure, while warm airrises Cool airis heavier than warm air. Cool airsinks down from an area of hours by measuring the air pressure. called a barometer. If you have one at home, it is probably an lightly in the morning, the needle points to the weatheryou can expect that day. The instrument used to measure changes in air pressure is dial marked Fine, Fair and Stormy. If you tap the glass aneroid barometer. There s a needle behind a glass-covered You can forecast what the weather will be like for the next few How do barometers work? high pressure warm air areas of high pressure to areas of low pressure. Temperature On the surface of the earth, or near it, air always moves from therefore less air pressure. down, it leaves behind an area of high pressure. has a great effect on air pressure. As warm air rises, it produce an area of low pressure near the ground. As the air pressure changes from place to place, and from day to day, it helps mov air across the earth s surface all the time. As cooler air moves pressure is less. This is because there is less air above you, anc or even if you go up to the top of a tall skyscraper, the air Find out more by looking at Look out of your window. Is the air moving? It is probably 80 Whatisairpressure? pages moving enough to make the branches on the trees sway

stays in the tube. It is held there by the air pressure at the end down in a small dish of mercury.

As the air pressure changes, the column of mercury moves up or down.

35 81 ofthe weather. instrument for accurate forecasting The mercury barometer is an pressure sensitive to changes in airpressure. glass small metal chamber which is The aneroid barometer contains a glass tube column of mercury stays in the tube. It is held there by the air pressure at the end down in a small dish of mercury. Some of the mercury surface of the mercury in the dish. As the air pressure changes, the column of mercury moves up or down. A scale A mercury barometer measures the air pressure more chamber is so thin that small changes in the air pressure accurately. Along, glass tube is filled with mercury, a silvery outside it make the metal bend. This makes the needle turn liquid metal. The tube is sealed at one end, and placed open beside the tube shows the pressure measurements. which almost all the air has been removed. The metal of the round and point to a new position on the dial. Inside the aneroid barometer is a metal box, or chamber, from Types of barometers

36 Measuring Mr Pressure Barometers are used to measure air pressure. Barometer latex balloon (tapeth Gass Tube Warcury Vacuum elastic band empty juice cart scal Balanced and Unbalanced Forces the inside of a closed container experiences a lower air pressure than the air pressure pushing on the outside, the walls of the container will buckle and cave in. If

37 Part E: How do fluids behave? Before you continue, the rest of this it s activity on the next page. important to learn some of the key words that section. Read these definitions carefully and then complete the will be used in Viscosity Viscosity is a word used to describe how thick a fluid is. A fluid that is thick Is very viscous and fluid that Is thin is not very viscous. The viscosity of fluid affects Its flow rate (how fast it moves when it is poured). a a I Density Density Is a word used to describe how close together, or tightly-packed, the particles (tiny pieces) In a fluid (or other material) ore. The more particles there are In a small amount of fluid, the more dense it Is, Fluids with fewer particles in the same amount of (so they are less tightly-packed) are less dense, space $4 Buoyancy Buoyancy Is a word used to explain whether things will float or sink in a fluid. The fluid s buoyant force is how much it pushes up at objects (floating) to fight against gravity that pull them down (sinking). Even though buoyancy really describes the fluid, we often use It to describe how the objects behave. Things that are buoyant float and things that are not buoyant sink. + Compressibfllty Compressiblilty Is a word used to describe whether a fluid space. Liquid fluids cannot be compressed only gases smaller space). can can be squeezed into a smaller be compressed (squeezed into a Copyright Resource Development Scrvices Edmonton Public Sthools 2003 Grade 8 Mix and I low of Matter 8

2. How quickly a fluid flows is called its viscous is very 1. A fluid that is very thick is very.

How do you think viscosity affects flow rate? Explain your answer. 10. Do you think the density of a fluid affects its buoyant force? Explain your answer. Predidil 9.

Buoyancy is a word used to describe whether an object will fight against gravity making them sink. 6. A fluid s force describes how much it pushes up at objects to 5.

38 2. How quickly a fluid flows is called its viscous is very 1. A fluid that is very thick is very. A fluid that is not very 9 (:op;right Resource 1)evelopment Senrices, Edmonton Public Schools, Grade 8 Mix and Now of Matter 11. How do you think viscosity affects flow rate? Explain your answer. 10. Do you think the density of a fluid affects its buoyant force? Explain your answer. Predidil 9. fluids can t be compressed but can. can be squeezed into a smaller space. 8. is a word used to describe whether a fluid or 7. Buoyancy is a word used to describe whether an object will fight against gravity making them sink. 6. A fluid s force describes how much it pushes up at objects to 5. is a word that describes how close together (or tightlypacked) particles are. 4. Fluids with a lot of particles in a small amount of space are very 3. is a word that describes how thick or thin a fluid is. are there to help you check how many letters are in the missing words. Fill in the blanks in the following sentences with words from page eight. The blanks

learned about fluids to answer the question. Study this graphic and read the information below it.

Grade 8 Mix and Flow of Matter Explain your answer. 1.

the carbon dioxide bubbles rise to the top of the liquid and burst of pop is opened and poured into a

39 learned about fluids to answer the question. Study this graphic and read the information below it. Then, use what you have 13 Copyright Resource Development Services, Edmonton Public Schools, Grade 8 Mix and Flow of Matter Explain your answer. 1. What does a glass of pop tell us about the density of carbon dioxide gas? into the air. the carbon dioxide bubbles rise to the top of the liquid and burst of pop is opened and poured into a glass (like the picture above), gas (another fluid) is dissolved in the liquid. Once a bottle or can Once the liquid Is added to a bottle or can of pop, carbon dioxide 4%

Student Exploration: Archimedes Principle

Name: Date: Student Exploration: Archimedes Principle Vocabulary: Archimedes principle, buoyant force, density, displace, mass, volume, weight Prior Knowledge Questions (Do these BEFORE using the Gizmo.)