1. Chapter 13 Table of Contents Section 1 Temperature
Heat and Temperature
Table of Contents
Section 1 Temperature
Section 2 Energy Transfer
Section 3 Using Heat

2. Chapter 13
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.

3. HEAT VS TEMP

4. Temperature and Energy
Chapter 13
Section 1 Temperature
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.

5. Temperature and Energy, continued
Chapter 13
Section 1 Temperature
Temperature and Energy, continued
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).
Celsius-Kelvin Conversion Equation
T = t + 237

6. Fahrenheit Conversion
C to F conversion
TF = 1.8tc
F to C conversion
Tc = Tf / 1.8

7. Chapter 13
Section 1 Temperature
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.
List the given and the unknown values.
Given:
t = 57.8ºC
Unknown:
TF = ?ºF
T = ?K

8. Chapter 13 Math Skills, continued
Section 1 Temperature
Math Skills, continued
2. Write down the equations for temperature conversions.
TF = 1.8t
T = t + 273
3. Insert the known values into the equations, and solve.
TF = (1.8  57.8) = = 136ºF
T = = 331 K

9. Relating Temperature to Energy Transfer
Chapter 13
Section 1 Temperature
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.

10. Chapter 13
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.

11. Methods of Energy Transfer
Chapter 13
Section 2 Energy Transfer
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.

12. Methods of Energy Transfer, continued
Chapter 13
Section 2 Energy Transfer
Methods of Energy Transfer, continued
Thermal Conduction
Conduction involves objects in direct contact.
Conduction takes place when two objects that are in contact are at unequal temperatures.

13. Methods of Energy Transfer, continued
Chapter 13
Section 2 Energy Transfer
Methods of Energy Transfer, continued
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.

14. Methods of Energy Transfer, continued
Chapter 13
Section 2 Energy Transfer
Methods of Energy Transfer, continued
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.
Much of the energy we receive from the sun is transferred by radiation.

15. Conductors and Insulators
Chapter 13
Section 2 Energy Transfer
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.

16. Chapter 13
Section 2 Energy Transfer
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 = cmDt

17. Chapter 13
Section 2 Energy Transfer
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: Dt = 37ºC – 25ºC = D12ºC = D12 K
DT = 12 K
m = 420 kg
c = 4186 J/kg• K (from table in textbook)
Unknown: energy = ? J

18. Chapter 13 Math Skills, continued
Section 2 Energy Transfer
Math Skills, continued
2. Write down the specific heat equation.
energy = cmDt
3. Substitute the specific heat, mass, and temperature change values, and solve.

19. Chapter 13
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.

20. Chapter 13 Heating and Cooling
Section 3 Using Heat
Heating and Cooling
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.
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.

21. Chapter 13 Air Conditioner 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.

22. Chapter 13 Heating Systems
Section 3 Using Heat
Heating Systems
Most heating systems use a source of energy to raise the temperature of a substance such as air or water.
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.

23. Heating Systems, continued
Chapter 13
Section 3 Using Heat
Heating Systems, continued
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.

24. Heating Systems, continued
Chapter 13
Section 3 Using Heat
Heating Systems, continued
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.

25. Heating Systems, continued
Chapter 13
Section 3 Using Heat
Heating Systems, continued
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.

26. Chapter 13 Cooling Systems
Section 3 Using Heat
Cooling Systems
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.

27. Chapter 13
Section 3 Using Heat
Heat Engines
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.

28. Internal Combustion Engine
Chapter 13
Section 3 Using Heat
Internal Combustion Engine

29. Chapter 13
Section 3 Using Heat
Concept Mapping

30. Understanding Concepts
Chapter 13
Standardized Test Prep
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.

31. Understanding Concepts
Chapter 13
Standardized Test Prep
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.

32. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
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.

33. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
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.

34. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
Understanding Concepts, continued
3. What transfer method carries energy from the sun to Earth?
A. conduction
B. convection
C. insulation
D. radiation

35. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
Understanding Concepts, continued
3. What transfer method carries energy from the sun to Earth?
A. conduction
B. convection
C. insulation
D. radiation

36. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
Understanding Concepts, continued
4. Why does the temperature of hot chocolate decrease faster if you place a metal spoon in the liquid?

37. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
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.

38. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
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.

39. Understanding Concepts, continued
Chapter 13
Standardized Test Prep
Understanding Concepts, continued
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.

40. Chapter 13 Reading Skills Standardized Test Prep
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.
6. How does the specific heat of water affect its ability to moderate coastal temperatures?

41. Chapter 13 Reading Skills Standardized Test Prep
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.
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.

42. Interpreting Graphics
Chapter 13
Standardized Test Prep
Interpreting Graphics
7. What form of heat transfer is represented by this illustration?
F. conduction
G. convection
H. insulation
I. radiation

43. Interpreting Graphics
Chapter 13
Standardized Test Prep
Interpreting Graphics
7. What form of heat transfer is represented by this illustration?
F. conduction
G. convection
H. insulation
I. radiation