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 Temperature and Energy Temperature is a measure of how hot (or cold) something is. –Average kinetic energy of the particles Thermometer measures temperature. Chapter 13 Section 1 Temperature
Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Measuring 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, water freezes at 0ºC and boils at 100ºC 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 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 Temperature Scales Chapter 13 Section 1 Temperature
Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Temperature and Heat 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 Methods of Energy Transfer 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 Methods of Energy Transfer, continued Section 2 Energy Transfer Radiation Radiation is energy transferred as heat in the form of electromagnetic waves. Unlike conduction and convection, radiation does not involve the movement of matter. Radiation is therefore the only method of energy transfer that can take place in a vacuum. Chapter 13
Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparing Convection, Conduction, and Radiation Section 2 Energy Transfer Chapter 13
Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparing Convection, Conduction, and Radiation Section 2 Energy Transfer 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. –Most metals are good conductors. Poor conductors are called insulators. Gases Liquids Some solids, such as rubber and wood 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 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 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 Machines transfer energy as heat from one place to another. –Furnace, air-conditioner, refrigerator, ect. First law of thermodynamics states that the total energy used in any process is conserved. Second law of thermodynamics states that heat always moves from an object at a higher temperature to an object at a lower temperature. Section 3 Using Heat Heating and Cooling 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. 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 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 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 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 Heating Systems Section 3 Using Heat Chapter 13
Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Refrigeration Section 3 Using Heat 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. Section 3 Using Heat Heat Engines Chapter 13
Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Using Heat Internal Combustion Engine Chapter 13
Four Stroke
Two Stroke
Diesel
Rotary Engine
Rocket/Jet
Scram Jet
Turbo Charger
Super Chargers