California science grade 5 (8)

Chapter Chapter The Sun produces more energy in one second than all the people who ever lived have ever used CHAPTER Heat Energy How does heat move from one object to another? 158 Lesson Heat Flow PAGE 162 Lesson Waves PAGE 174 Lesson Fuels: Our Major Energy Source PAGE 186 Lesson Heat Transfer in Solids and Fluids PAGE 198 PS Heat moves in a predictable flow from warmer objects to cooler objects until all the objects are at the same temperature 159 Literature MAGAZINE ARTICLE ELA R 6.2.3 Connect and clarify main ideas by identifying their relationships to other sources and related topics • ELA W 6.2.1 Write narratives 160 from SCHOLASTIC NEWS by Fiona McCormack A group of strange-looking cars recently zipped through Australia The vehicles looked like spaceships, but they were solar-powered cars The cars and their drivers were competing in the World Solar Challenge, a 1,877-mile solar-car race The cars, with one driver in each, raced from Darwin to Adelaide, Australia Twenty-two teams from 11 countries competed The winning car, from the Netherlands, finished in about 29 hours Solar cars run on sunlight instead of gasoline Flat solar panels line the outside of the cars The panels catch sunlight and turn it into electricity to power the cars’ motors With this power, solar cars can travel up to 74 miles per hour Solar cars aren’t advanced enough to replace gas-powered cars yet But the race demonstrates that their future is bright Write About It Response to Literature This article describes how people use energy from the Sun to run solar cars In what other ways people use the Sun’s energy? Is the Sun’s energy always useful? Write a personal narrative about how the Sun affects your life What role does the Sun play in your activities? -Journal Write about it online @ www.macmillanmh.com 161 Lesson Heat Flow Have you ever been to the desert? During the day the air and the ground can be very hot At night the air cools quickly However, if you touch the ground, you’ll find that it stays warm for a while longer than the air does How reliable is your sense of touch in determining how hot or cold an object is? 162 ENGAGE PS 3.a Students know energy can be carried from one place to another by heat flow or by waves, including water, light and sound waves, or by moving objects How can you measure heat flow? Materials Make a Prediction Do you think heat flows between warm objects and cool objects? What will happen if a jar of cool water is set into a bowl of room-temperature water? Write your answer as a prediction in the form “If a jar of warm water is set into a bowl of room-temperature water, then If a jar of cool water is set into a bowl of room-temperature water, then ” • large bowls • jars Test Your Prediction • thermometers Fill one jar with 30°C water Fill a second jar with 10°C water • watch or stopwatch Measure Place each jar into a separate bowl of room-temperature water 22°–24°C Record the starting temperatures of the water in the bowls and jars • water Step Experiment Record the temperatures of the containers every minutes for 20 minutes Record your observations When you think the temperatures will stop changing? Draw Conclusions Analyze Make a line graph that shows how the temperature of the water in each jar and each bowl changed over time Step Analyze What happened to the temperature of the jar with warm water? Where did the heat go? Explore More What you think will happen if you place a jar of warm water into a bowl of ice water? Make a prediction and test it Then analyze and present your results IE 7.c Construct appropriate graphs from data and develop qualitative statements about the relationship between variables • IE 7.d Communicate the steps and results from an investigation in written reports and oral presentations 163 EXPLORE ▶ Main Idea PS 3.a Heat energy flows from a warmer object to a cooler object until both are the same temperature ▶ Vocabulary energy, p 164 kinetic energy, p 165 potential energy, p 165 temperature, p 166 heat, p 167 heat flow, p 168 insulation, p 170 -Glossary @ www.macmillanmh.com ▶ Reading Skill Compare and Contrast 2WTTS`S\b /ZWYS 2WTTS`S\b How is energy related to motion? You know that water can exist as a solid (ice), a liquid (liquid water), or a gas (water vapor) Did you know that almost all matter can exist as a solid, a liquid, or a gas? Why? Matter is made of molecules that are always moving Whether the molecules form a solid, a liquid, or a gas depends on how close together they are and how fast they move Molecules usually move faster in gases and slower in liquids and solids In solids molecules vibrate back and forth In gases molecules move in straight lines until they bump into other molecules In liquids molecules show a mix of both of these types of motion The motion of molecules is a type of energy Energy is the ability to bring about changes or to work It takes energy to move yourself up a hill It takes energy to light a house or cook a dinner It also takes energy to change ice into water or water into water vapor Molecules in a Solid, a Liquid, and a Gas Explore heat flow with a chef liquid solid gas The molecules in solids, liquids, and gases move at different speeds 164 EXPLAIN Two Kinds of Energy A skateboarder swoops down a hill, moving faster and faster The energy of any moving object is called kinetic energy (ki•NET•ik EN•uhr•jee) A skateboarder has a lot of kinetic energy as she moves down a hill The molecules of a gas have a lot of kinetic energy, too, because they are moving quickly ▼ As the girl moves downhill, her potential energy is converted into kinetic energy When the skateboarder skates up the hill, she is storing energy The energy stored in an object by changing its location is called potential energy Moving an object upward against gravity is one way to give it potential energy At the top of the hill, as the skateboarder waits to start downhill, she has the most potential energy Any moving object, from a molecule to a car, has energy due to its motion When you kick a soccer ball, it has kinetic energy as it sails across the field Quick Check Compare and Contrast How are kinetic energy and potential energy similar and different? Critical Thinking What kind of energy would a person at rest have, and why? 165 EXPLAIN How is temperature different from heat? If you place a thermometer in boiling water, it registers 100°C (212°F) The thermometer measures the temperature of the water The temperature of a substance is the average kinetic energy of its molecules Molecules in all substances are constantly in motion The molecules in a gas move about rapidly, colliding with one another They have a great deal of energy The molecules in a solid vibrate in place They have less energy than the molecules in a gas Some molecules in a substance may move faster or slower than other molecules Scientists calculate the average speed to determine the molecules’ average kinetic energy The average kinetic energy of the molecules determines how much heat a material has The average kinetic energy is its temperature 166 EXPLAIN Before a balloon can fly, the air inside it must be heated The molecules in the air inside the balloon move farther apart Now the air in the balloon is not as dense as the air that surrounds the balloon The balloon floats high into the sky Convert measurements For accurate calculations use these measurements: mi/gal = 0.425 km/L km/L = 2.35 mi/gal Hybrid cars use less energy from fossil fuels by using a combination of gasoline and electricity from a battery These cars can be very fuel efficient Car buyers look carefully at fuel-efficiency information This information is usually written in miles per gallon (mi/gal) or kilometers per liter (km/L) The farther the car can travel on gallon or liter of gasoline, the more fuel efficient the car is This information helps a car buyer determine how much it might cost to buy fuel to drive a car for a year Solve It The table lists the fuel use of vehicles in mi/gal or km/L In order to compare efficiency, all the measurements must be in a single system Complete the table by converting mi/gal to km/L or km/L to mi/gal to fill in the missing information Which car is the most fuel efficient? Which is the least? Hybrid car B travels 46 miles on a gallon of gasoline How many gallons are needed for the car to travel 500 miles? ▶ To convert mi/gal to km/L, multiply the mi/gal by 0.425 22 mi/gal × 0.425 = 9.35 km/L ▶ To convert km/L to mi/gal, multiply the km/L by 2.35 9.35 km/L × 2.35 = 21.97 mi/gal Vehicle Fuel Use (in mi/gal) Sports car A Sports car B 9.8 18 Hybrid car A Hybrid car B 15.3 46 Sedan A Sedan B Fuel Use (in km/L) 16.2 20 Luxury car 5.2 Compact car A 15.3 Compact car B 29 Station wagon Sport utility vehicle 11.0 14 MA NS 6.1.2 Interpret and use ratios in different contexts (e.g., batting averages, miles per hour) to show the relative sizes of two quantities, using appropriate notations (a/b, a to b, a:b) • MA AF 6.2.1 Convert one unit of measurement to another (e.g., from feet to miles, from centimeters to inches) 197 EXTEND Lesson Heat Transfer in Solids and Fluids When a large block of ice falls off a glacier and splashes into the sea, the nearby water gets colder What you think happens to the air above the iceberg and the sea? 198 ENGAGE PS 3.c Students know heat flows in solids by conduction (which involves no flow of matter) and in fluids by conduction and by convection (which involves flow of matter) Materials How does heat flow from one material to another? Make a Prediction What will happen when two objects of different temperatures are placed together? Will heat be transferred? Write your answer as a prediction in the form “If heat moves from hot to cold, then ” Test Your Prediction Hold a liquid-crystal thermometer card against the back of your hand, and observe what happens to the card as it warms up Record color changes, if any • liquid-crystal thermometer cards • quarter Warm a quarter in your hands and place it on the table Place a liquid-crystal thermometer card on top of the quarter Record any changes Hold a liquid-crystal thermometer card above a cup of hot water Note any changes What shape is the colored region? How is this different from the colored regions in steps and 2? • cup of hot water • ice cube Step Hold an ice cube about centimeter above a thermometer card What happens now? Draw Conclusions Analyze How would you explain what you observed? Did your observations support your prediction? Does heat flow between two materials when they are touching? When they are not touching? Step Explore More What would happen if you repeated step and placed a second card on top of the first? Make a prediction and test it Then analyze and present your results IE 7.b Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data • IE 7.e Recognize whether evidence is consistent with a proposed explanation 199 EXPLORE How is heat transferred? ▶ Main Idea PS 3.c Heat flows in solids by conduction and in fluids by conduction and convection ▶ Vocabulary conduction, p 200 convection, p 202 buoyancy, p 202 convection current, p 203 -Glossary @ www.macmillanmh.com ▶ Reading Skill Compare and Contrast 2WTTS`S\b /ZWYS 2WTTS`S\b A glassmaker uses fire to melt the glass before shaping it 200 EXPLAIN Heat transfer is measured by changes in temperature Objects that are near each other will eventually have the same temperature Heat travels from warmer objects to cooler objects until the objects are the same temperature Conduction Conduction is the movement of energy through direct contact This means that two materials must be touching for heat to be conducted from one material to the other Conduction is the only way heat can travel through solids Heat Transfer Heat is transferred from the burner to the frying pan to the food through conduction Reading Photos How does the food in the pan cook? Clue: What role does the frying pan play? All atoms in a solid vibrate in place and transfer their movement to one another When a faster-moving, warmer atom collides with a slowermoving, cooler atom, it passes some of its kinetic energy to the slowermoving atom As a solid such as the burner on an electric stove heats up, its atoms vibrate more quickly, and its temperature rises If you put a pot on the burner, these vibrating atoms will transfer some of their motion from the burner to the atoms on the bottom of the pot The faster-vibrating atoms on the bottom of the pot then transfer energy to those next to them Energy is transferred from atom to atom until the entire pot is hot Atoms in liquids and gases are not as close to each other as they are in solids Their vibrations cause them to move around Quick Check Compare and Contrast How is heat transferred between two solids at different temperatures? At the same temperature? Critical Thinking How does the vibration of atoms conduct heat through a solid? 201 EXPLAIN What is convection? When you heat a pot of soup, some of the heat is transferred, or conducted, through direct contact of the pot with the soup However, most of the heat is transferred as the heated soup at the bottom rises and flows throughout the pot The transfer of energy by the flow of a liquid or a gas is called convection Convection can occur in liquids and gases but not in solids Convection occurs because most gases and liquids (both of which are known as fluids) become less dense when they are heated In the atmosphere, warmer air rises because it has a lower density than cooler air Cooler air is denser and sinks Hotter, less-dense fluid rises through colder, denser fluid because of the hotter fluid’s greater buoyancy Buoyancy is an upward force on an object or a substance that is in a liquid or a gas Buoyancy and density are directly related For example, oil is less dense and more buoyant than water, so oil floats on the water’s surface ▼ The air in the inner tube is less dense than the water, so the girl can float 202 EXPLAIN Conduction and Convection abSO[W`]\ 1]\dSQbW]\Qc``S\baW\3O`bV¸a[O\bZS QOcaS[]dS[S\bW\bVSQ`cab Q]\dSQbW]\Qc``S\b b`S\QV Q`cab 6SObWab`O\aTS``SR PgQ]\RcQbW]\eVS\ bVSV]bW`]\b]cQVSa bVSQZ]bV [O\bZS Q]`S b`S\QV b`S\QV `WRUS Reading Diagrams How is heat transferred in the liquid part of Earth? Clue: The labels can help you interpret the diagram Convection Currents As a hot fluid rises away from its source of heat, it may cool, become denser, sink back to the heat source, and be warmed again The resulting circulation of hot and cold fluids is called a convection current This current helps warm a pot of soup evenly, even though most of the heat is applied to the bottom of the pot that is touching the burner Convection currents can move through gases or liquids In the atmosphere warmer air carries heat energy upward The warm air rises because of its lower density Cooler air is denser and sinks However, density is not the same as weight An object can be denser than another but weigh less Quick Check Compare and Contrast What is the difference between conduction in a solid and convection in a liquid or gas? Critical Thinking How does a convection current carry heat throughout a liquid or gas? 203 EXPLAIN Which warms faster? Write a hypothesis about which material—water or plastic foam— you think will warm up more quickly Make a list of variables that affect how rapidly the two materials warm up Fill a beaker half full of water and another half full of plastic-foam peanuts Place a thermometer in each beaker Record the starting temperatures Place both beakers under a desk lamp, and turn the lamp on Measure Take the temperature of each beaker after 2, 4, 6, and minutes Infer When did you observe a change in temperature? What was the result of your experiment? Do your observations support your hypothesis? Do some materials warm faster than others? It takes less energy to warm some materials than others The amount of energy needed to increase the temperature of a substance one degree is a physical property Some kinds of matter, such as water, take a lot of energy to increase their temperature Other kinds of matter require less energy Scientists call this physical property specific heat capacity Since it takes a lot of heat to increase the temperature of water one degree, water is often used for heating and cooling in homes and automobiles The table below lists some specific heat capacities Specific Heat Capacities Material Specific Heat Capacity Air 1.004 Aluminum 0.897 Copper 0.385 Water 4.181 Ice 2.114 Sand 0.835 Wood 0.42 Brick 0.84 Concrete 0.88 Quick Check Compare and Contrast Which material in the table takes the least amount of energy to warm up? Critical Thinking On a sunny day why does sand at the beach heat up before the water? 204 EXPLAIN Summarize the Main Idea Conduction is the movement of energy through direct contact (p 200–201) Think, Talk, and Write Main Idea How does heat flow in solids, liquids, and gases? Vocabulary Heat transfer by direct contact is called Compare and Contrast What is the abSO[W`]\ 1]\dSQbW]\Qc``S\baW\3O`bV¸a[O\bZS QOcaS[]dS[S\bW\bVSQ`cab Q]\dSQbW]\Qc``S\b b`S\QV Q`cab 6SObWab`O\aTS``SR PgQ]\RcQbW]\eVS\ bVSV]bW`]\b]cQVSa bVSQZ]bV [O\bZS Q]`S b`S\QV b`S\QV Convection is the transfer of energy by the flow of a liquid or a gas (p 202–203) difference between conduction and convection? 2WTTS`S\b /ZWYS 2WTTS`S\b `WRUS Specific heat capacity is the energy required to increase the temperature of gram of material degree Critical Thinking Explain why many metal pots and pans have wooden or plastic handles Test Practice Use the table on page Make a Study Guide Take a sheet of paper and tape your lesson study guides as shown Use the study guides to answer the questions on these pages Writing Link 204 Which of the following will take the most energy to increase its temperature? A concrete B brick C aluminum D copper Test Practice What is the upward force on an object that is in a liquid or a gas called? A buoyancy B conduction C convection D energy Math Link Explanatory Letter Arrange a Data Series Write a letter to the builders of a new house Explain what materials they should use to limit heat transfer in the new house Arrange the items in the chart on page 204 from greatest to least specific heat capacity Find the mean and median of the series -Review Summaries and quizzes online @ www.macmillanmh.com 205 EVALUATE Materials Inquiry Structured What are conduction and convection? Make a Prediction metal rod thermal strip Heat energy can move through solids by a process called conduction In fluids heat energy can move by conduction and through convection currents Heat energy moves at different rates through different solids and fluids Metals are considered good conductors because heat energy moves through them rapidly How can you measure conduction of energy in a solid? Write your answer as a prediction in the form “If heat moves through a solid by conduction, then you can measure the movement by ” Be Careful Be careful while handling warm water Clean up spills immediately ruler transparent tape Test Your Prediction Measure Use the ruler to measure the length of the metal rod Use a marker to place a dot at each inch along the length of the metal rod Record the length of the rod, and draw a picture of it in your journal Place your thumb on the thermal strip for second Record the color change in your journal graph paper markers Step Use transparent tape to attach the thermal strip to the rod Line up the end of the strip with the first mark You will need to be able to see the marks on the rod throughout the activity Step Step Place one end of the rod in a cup of warm water Start a timer, and record how many seconds it takes the changing color on the thermal strip to travel to each mark Repeat step two more times, and record your data 206 EXTEND IE 7.c Construct appropriate graphs from data and develop qualitative statements about the relationships between variables Draw Conclusions Graph Construct a line graph, and plot your three trials on the graph Analyze Using your data describe the process of conduction Describe any trends or differences you saw among the three trials Infer What you think would happen if the water you used were hotter? Inquiry Guided What causes convection currents in water? Form a Hypothesis How convection currents begin in a body of water? Write your answer as a hypothesis in the form “If warm water is added to cooler water, then ” Test Your Hypothesis Design an experiment to investigate how heat energy moves through convection currents Write out the materials you will need and the steps you will follow Carry out your experiment, and record your results and observations Draw Conclusions Did your experiment support your hypothesis? Why or why not? Present your results to your classmates Inquiry Open What are some conductive properties of metals? For example, are some metals better conductors than others? Think of a question, and design an experiment to investigate it Plan your experiment to test one variable, or one item being changed Write out the steps so another group could try it by following your instructions Remember to follow the steps of the scientific process Ask a Question Form a Hypothesis Test Your Hypothesis Draw Conclusions 207 EXTEND CHAPTER Review Summarize the Main Ideas Heat energy flows from a warmer object to a cooler object until both objects are the same temperature (pp 162–171) Energy moves from one place to another by heat flow or by waves All waves have a wavelength, a frequency, and an amplitude Fill each blank with the best term from the list biomass conversion, p 189 conduction, p 200 convection current, p 203 electromagnetic waves, p 182 frequency, p 177 heat, p 167 kinetic energy, p 165 potential energy, p 165 The movement of energy from one substance to another is PS 3.a (pp 174–183) When a fuel burns, stored chemical energy changes into heat energy and light energy The movement of energy through direct contact is PS 3.c A boulder perched at the top of a cliff has PS 3.a (pp 186–195) Heat flows in solids by conduction and in fluids by conduction and convection (pp 198–205) Make a Study Guide Take a sheet of paper and tape your lesson study guides as shown Use the study guides to answer the questions on these pages 208 Alternating currents of electric and magnetic fields that carry energy from the Sun to Earth are called PS 3.a The method of changing plant and animal materials into high-quality fuels is called PS 3.b Warm fluids rising and cooling while denser fluids are sinking and warming is an example of a(n) PS 3.c The energy of any moving object, such as a molecule in a gas, is called PS 3.a The number of complete wave vibrations, or cycles, per unit of time is the PS 3.a -Review Summaries and quizzes online @ www.macmillanmh.com Answer each of the following in complete sentences Sequence Describe the path of a sound wave from a ringing school bell to your brain PS 3.a 10 Cause and Effect Describe what a hockey game would look like if there were no friction PS 3.b 11 Infer Suppose you had to hold up a very heavy suitcase for several hours without moving Why is this situation not considered to be work? PS 3.b 12 Compare and Contrast Explain how sound waves and light waves are alike and different PS 3.a 13 Explanatory Writing Compare the energy conversions that occur when people’s bodies use food as fuel with the energy conversions that occur when an automobile uses gasoline for fuel PS 3.b What a Ride! La Marcus Adna Thompson created the first successful roller coaster, introduced at Coney Island, in New York City, in 1884 Your goal is to think like an inventor and design your own roller coaster What to Do Design your own roller coaster, with at least one big hill and several smaller hills Think about how you will get the cars to the top of the first hill Identify the potential and kinetic energy along the path of your roller coaster Analyze Your Results ▶ Where would you find the maximum potential energy on your roller coaster? Where is the minimum potential energy and maximum kinetic energy? ▶ Where on your roller coaster is work being done? How does heat move from one object to another? 16/>B3@! 209 Why the molecules of a gas have a higher temperature than the molecules of a solid? PS 3.a A B C D A They move more rapidly and have more energy B They vibrate in place, rubbing against each other C They move in a straight line and vibrate in place D They move less rapidly and are closer together a b c d A The temperature of metals does not change much when heat is added B Metals absorb heat but not distribute it evenly C Metals absorb heat and distribute it evenly D Metals prevent heat from flowing in or out of a material 210 What happens to stored chemical energy when a fuel burns? PS 3.b of it is left B The energy stays in the form of chemical energy C The energy turns into heat energy and light energy D The energy turns into potential energy and kinetic energy = Why are metals good conductors of heat? PS 3.c in a straight path to your ear back and forth from the source outward in all directions upward from the source A The energy decreases until no part Which part of the picture below shows the wavelength? PS 3.a A B C D What is the best description of how sound waves travel? PS 3.a In the chemical reaction for burning methane, which of these is a reactant? PS 3.b A B C D water vapor oxygen carbon dioxide heat How does heat travel through solids? PS 3.c A B C D conduction convection radiation emission BW[SW\[WZZWaSQ]\Ra 8 A student hypothesizes that sound travels faster through glass than through plastic or wood He performs an experiment and gathers his data The following graph shows his data 10 Two objects are placed together so that their sides are touching One object is 30°C warmer than the other object What will happen? PS 3.c A Coolness will flow from the cooler object to the warmer object B Heat will flow from the warmer object to the cooler object C There will be no change, because solid objects not transfer heat D They will heat up until they are both 30°C warmer than before  & $ "  >ZOabWQ 5ZOaa E]]R 11 ;ObS`WOZ Which conclusion is correct? A B C D IE 7.e The table below shows the specific heat capacity of different materials Materials with higher values need more energy to raise their temperature Wood is better than plastic or glass Glass is better than plastic or wood Sound travels fastest through wood Sound travels fastest through plastic Material Fuel stored in food is used to help you work When you push a ball up a hill, an energy change takes place in the ball What is this energy change that is taking place? PS 3.b Aluminum 0.897 Copper 0.385 Wood 0.42 Brick 0.84 Which material requires the most energy to raise its temperature? PS 3.c A Kinetic energy is converted into potential energy B Potential energy is converted into kinetic energy C Kinetic energy is converted into compression waves D Chemical energy is converted into kinetic energy Specific Heat Capacity A B C D 12 aluminum copper wood brick Insulation is used to A B C D PS 3.c conduct thermal energy measure thermal energy prevent heat flow increase heat flow Materials prepared by PASS at 211 ... until both are the same temperature ▶ Vocabulary energy, p 164 kinetic energy, p 1 65 potential energy, p 1 65 temperature, p 166 heat, p 167 heat flow, p 168 insulation, p 170 -Glossary @ www.macmillanmh.com... predictable flow from warmer objects to cooler objects until all the objects are at the same temperature 159 Literature MAGAZINE ARTICLE ELA R 6.2.3 Connect and clarify main ideas by identifying their relationships...CHAPTER Heat Energy How does heat move from one object to another? 158 Lesson Heat Flow PAGE 162 Lesson Waves PAGE 174 Lesson Fuels: Our Major Energy Source PAGE 186