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Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. You may exit the slide show at any time by pressing the Esc key. How to Use This Presentation

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Temperature Objectives Define temperature in terms of the average kinetic energy of atoms or molecules. Convert temperature readings between the Fahrenheit, Celsius, and Kelvin scales. Recognize heat as a form of energy transfer. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer 1.In drawing 1, which bowl would feel warm to your hands? Which bowl would feel cool? We use words like hot and cold, long and short, and heavy and light every day to describe the differences between things. In science, however, this is often not accurate enough and leads to confusion. Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer, continued 3. A person from Seattle tells his friend from Florida that the weather in Seattle is somewhat warm. When the friend arrives for a visit, he finds that he is uncomfortably cool wearing the shorts he packed. What would be a more effective way for the person from Seattle to explain the weather? 2.In drawing 2, which bowl would feel warm to your hands? Which would feel cool? Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Temperature and Energy Temperature is a measure of how hot (or cold) something is. Specifically, it is a measure of the average kinetic energy of the particles in an object. As the average kinetic energy of an object increases, its temperature will increase. A thermometer is an instrument that measures and indicates temperature. Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Temperature and Energy, continued Fahrenheit and Celsius are common scales used for measuring temperatures. On the Fahrenheit scale, water freezes at 32ºF and boils at 212ºF. The Celsius scale, which is widely used in science, gives a value of 0ºC to the freezing point of water and a value of 100ºC to the boiling point of water at standard atmospheric pressure. Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Temperature and Energy, continued Fahrenheit-Celsius Conversion Equations A degree Celsius is 1.8 times as large as a degree Fahrenheit. Also, the temperature at which water freezes differs for the two scales by 32 degrees. T F = Fahrenheit temperature t = Celsius temperature Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Temperature and Energy, continued Celsius-Kelvin Conversion Equation T = t + 273 T = Kelvin temperature t = Celsius temperature The Kelvin scale is based on absolute zero. Absolute zero is the temperature at which molecular energy is at a minimum (0 K on the Kelvin scale or –273.16ºC on the Celsius scale). Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Math Skills Temperature Scale Conversion The highest atmospheric temperature ever recorded on Earth was 57.8ºC. Express this temperature both in degrees Fahrenheit and in kelvins. 1.List the given and the unknown values. Given: t = 57.8ºC Unknown: T F = ?ºF T = ?K Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Math Skills, continued 2. Write down the equations for temperature conversions. Chapter 13 Section 1 Temperature T F = 1.8t + 32.0 T = t + 273 3. Insert the known values into the equations, and solve. T F = (1.8  57.8) + 32.0 = 104 + 32.0 = 136ºF T = 57.8 + 273 = 331 K

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Relating Temperature to Energy Transfer Temperature changes indicate an energy transfer. Heat is the energy transferred between objects that are at different temperatures. The transfer of energy as heat always takes place from a substance at a higher temperature to a substance at a lower temperature. For example, if you hold a glass of ice water in your hands, energy will be transferred as heat from your hand to the glass. Chapter 13 Section 1 Temperature

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Energy Transfer Objectives Investigate and demonstrate how energy is transferred by conduction, convection, and radiation. Identify and distinguish between conductors and insulators. Solve problems involving specific heat. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer The three pictures all show examples of energy transfer. Answer the questions about what happens in each picture, and identify how the heat got from one object to another in each case. Section 2 Energy Transfer 1.Why is it a bad idea to drink hot cocoa out of a tin cup? Explain the energy transfers on the atomic level. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer, continued Section 2 Energy Transfer 2. What happens to your hand when you place it above a lighted candle? (Assume you are not touching the flame. Explain the energy transfers on the atomic level. Hint: Remember that warm air rises.) 3. When you sit near a fire, you can feel its warmth on your skin, even if you are in cool air. Does this sensation depend upon the fact that warm air rises? Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Methods of Energy Transfer The transfer of heat energy from a hot object can occur in three ways: Thermal conduction is the transfer of energy as heat through a material. Convection is the movement of matter due to differences in density that are caused by temperature variations. Radiation is the energy that is transferred as electromagnetic waves, such as visible light and infrared waves. Section 2 Energy Transfer Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Methods of Energy Transfer, continued Section 2 Energy Transfer Thermal Conduction Conduction involves objects in direct contact. Conduction takes place when two objects that are in contact are at unequal temperatures. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Methods of Energy Transfer, continued Section 2 Energy Transfer Convection Convection results from the movement of warm fluids. During convection, energy is carried away by a heated fluid that expands and rises above cooler, denser fluids. A convection current is the vertical movement of air currents due to temperature variations. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Conductors and Insulators Any material through which energy can be easily transferred as heat is called a conductor. Poor conductors are called insulators. Gases are extremely poor conductors. Liquids are also poor conductors. Some solids, such as rubber and wood, are good insulators. Most metals are good conductors. Section 2 Energy Transfer Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Specific Heat Specific heat describes how much energy is required to raise an object’s temperature. Specific heat is defined as the quantity of heat required to raise a unit mass of homogenous material 1 K or 1°C in a specified way given constant pressure and volume. Specific Heat Equation energy = (specific heat)  (mass)  (temperature change) energy = cm  t Section 2 Energy Transfer Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Math Skills Specific Heat How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the water’s temperature from 25°C to 37°C? 1. List the given and the unknown values. Given:  t = 37ºC – 25ºC =  12ºC =  12 K  T = 12 K m = 420 kg c = 4186 J/kg K (from table in textbook) Unknown: energy = ? J Section 2 Energy Transfer Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Math Skills, continued 2. Write down the specific heat equation. energy = cm  t 3. Substitute the specific heat, mass, and temperature change values, and solve. Section 2 Energy Transfer Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Using Heat Objectives Describe the concepts of different heating and cooling systems. Compare different heating and cooling systems in terms of their transfer of usable energy. Explain how a heat engine uses heat energy to do work. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer 1.You have learned that there is an energy change when a liquid evaporates. Will the area near the liquid get hotter or cooler as evaporation occurs? (Hint: Compare and contrast the molecular motion of particles as liquids and as gases.) Section 3 Using Heat One extremely cold winter day, the thermostat in the science classroom was set too low and the room was cold. The science teacher did not have the right tool to reset the thermostat, so she made a thin cloth cover for the thermostat, wet it, and placed it over the thermostat. Soon the room was comfortably warm. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer, continued 2.The thermostat is designed to turn the heater on when the temperature of the room falls below a certain temperature. How did putting the wet cloth over the thermostat turn the heater on so the room would get warmer? Section 3 Using Heat Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer, continued 3.Imagine a different situation in the same class, during the week before summer vacation. This time, it is very hot outside, but the thermostat is set so high that the air conditioner does not come on. Which of the following might help the thermostat trigger the air conditioner more frequently? a. use another wet cloth on the thermostat b. point a fan at the thermostat c. wrap the thermostat in a dark cloth that has been sitting by the windowsill d. wrap the thermostat in a dark cloth that has been kept in the refrigerator e. redirect air from the air conditioner vent away from the thermostat Section 3 Using Heat Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Heating a house in the winter, cooling an office building in the summer, or preserving food throughout the year is possible because of machines that transfer energy as heat from one place to another. These machines operate with two principles about energy that you have already studied: The first law of thermodynamics states that the total energy used in any process—whether that energy is transferred as a result of work, heat, or both—is conserved. Section 3 Using Heat Heating and Cooling The second law of thermodynamics states that the energy transferred as heat always moves from an object at a higher temperature to an object at a lower temperature. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Using Heat One example is an air conditioner. An air conditioner does work to remove energy as heat from the warm air inside a room and then transfers the energy to the warmer air outside the room. Air Conditioner Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Most heating systems use a source of energy to raise the temperature of a substance such as air or water. Section 3 Using Heat Heating Systems The human body is a heating system. Some of the energy from food is transferred as heat to blood moving throughout the human body to maintain a temperature of about 37°C (98.6°F). In central heating systems, heated water or air transfers energy as heat. Solar heating systems also use warmed air or water. Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu In the solar system shown here, a solar collector uses panels to gather energy radiated by the sun. This energy is used to heat water that is then moved throughout the house. This is an active solar heating system because it uses energy from another source, such as electricity, to move the heated water. Section 3 Using Heat Heating Systems, continued Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu In a passive solar heating system, energy transfer is accomplished by radiation and convection. In this example, energy from sunlight is absorbed in a rooftop panel. Pipes carry the hot fluid that exchanges heat energy with the air in each room. Section 3 Using Heat Heating Systems, continued Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu When energy can be easily transformed and transferred to accomplish a task, such as heating a room, we say that the energy is in a usable form. After this transfer, the same amount of energy is present, according to the law of conservation of energy. Yet less of it is in a form that can be used. In general, the amount of usable energy always decreases whenever energy is transferred or transformed. Insulation minimizes undesirable energy transfers. Section 3 Using Heat Heating Systems, continued Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu In all cooling systems, energy is transferred as heat from one substance to another, leaving the first substance with less energy and thus a lower temperature. A refrigerant is a material used to cool an area or an object to a temperature that is lower than the temperature of the environment. During each operating cycle, the refrigerant evaporates into a gas and then condenses back into a liquid. Section 3 Using Heat Cooling Systems Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A heat engine is a machine that transforms heat into mechanical energy, or work. Internal combustion engines burn fuel inside the engine. An automobile engine is a four-stroke engine, because four strokes take place for each cycle of the piston. The four strokes are called intake, compression, power, and exhaust strokes. Internal combustion engines vary in number of pistons. Section 3 Using Heat Heat Engines Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 1.What happens to the energy that is lost when an engine is less than 100% efficient? A.It is destroyed during combustion. B.It is converted to heat and transferred to the environment. C.It is converted to matter in the form of gases that enter the atmosphere. D.It is lost as friction between the tires of the vehicle and the surface of the road. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 1.What happens to the energy that is lost when an engine is less than 100% efficient? A.It is destroyed during combustion. B.It is converted to heat and transferred to the environment. C.It is converted to matter in the form of gases that enter the atmosphere. D.It is lost as friction between the tires ofthe vehicle and the surface of the road. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts, continued 2.What change occurs in matter when its temperature is increased? F.The specific heat of the material increases. G.Atoms and molecules in the material move faster. H.The attraction between atoms and molecules increases. I.The frequency of collisions between atoms and molecules decreases. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts, continued 2.What change occurs in matter when its temperature is increased? F.The specific heat of the material increases. G.Atoms and molecules in the material move faster. H.The attraction between atoms and molecules increases. I.The frequency of collisions between atoms and molecules decreases. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts, continued 4.Why does the temperature of hot chocolate decrease faster if you place a metal spoon in the liquid? Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts, continued 4.Why does the temperature of hot chocolate decrease faster if you place a metal spoon in the liquid? Answer: Metal is a good conductor of heat, so energy is transferred rapidly to the metal and from the metal to the air. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts, continued 5.Determine why you can’t cool your kitchen on a hot day by opening the refrigerator to let the cold air escape into the room. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts, continued 5.Determine why you can’t cool your kitchen on a hot day by opening the refrigerator to let the cold air escape into the room. Answer: The cooling system releases more heat into the room than it removes from the interior of the refrigerator. Standardized Test Prep Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The specific heat of water is very high compared to that of the soil and rock that make up land surfaces. In areas near a large body of water, the water does not heat as quickly as the land during the summer and does not cool as quickly as the land during the winter. This causes the climate in coastal areas to be generally milder than inland areas at the same latitude. For example, San Francisco has cooler summers and warmer winters than Sacramento, less than 150 km to the east. Standardized Test Prep Chapter 13 Reading Skills 6.How does the specific heat of water affect its ability to moderate coastal temperatures?

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reading Skills The specific heat of water is very high compared to that of the soil and rock that make up land surfaces. In areas near a large body of water, the water does not heat as quickly as the land during the summer and does not cool as quickly as the land during the winter. This causes the climate in coastal areas to be generally milder than inland areas at the same latitude. For example, San Francisco has cooler summers and warmer winters than Sacramento, less than 150 km to the east. Standardized Test Prep 6.How does the specific heat of water affect its ability to moderate coastal temperatures? Answer: The high specific heat means that water can store heat during warm months and release it when the land and air are cooler in winter. Chapter 13