Transfers and Transformations

Transcription

1 Chapter Introduction Lesson 1 Lesson 2 Lesson 3 Forms of Energy Energy Transfers and Transformations Particles in Motion Chapter Wrap-Up

2 What is the difference between energy transfers and energy transformations?

3 What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.

4 Do you agree or disagree? 1. An object sitting on a high shelf has no energy. 2. There are many forms of energy. 3. In most systems, no energy is transferred to the environment.

5 Do you agree or disagree? 4. Some forms of energy are replenished naturally. 5. Only particles that make up moving objects are in motion. 6. Thermal energy can be transferred in several ways.

6 Forms of Energy How do potential energy and kinetic energy differ? How are mechanical energy and thermal energy similar? What two forms of energy are carried by waves?

7 Forms of Energy energy potential energy chemical energy nuclear energy kinetic energy electric energy mechanical energy thermal energy wave sound energy radiant energy

8 Energy Energy influences everything in your life, including the climate, the economy, and your body. Scientists define energy as the ability to cause change.

9 Potential Energy Potential energy is stored energy due to the interaction between objects or particles. Objects have potential energy if they have the potential to cause change.

10 Objects have gravitational potential energy if they have mass and height above Earth s surface.

11 Potential Energy (cont.) Chemical energy is the energy stored in and released from the bonds between atoms. Your body breaks chemical bonds in foods and coverts the released energy into other forms of energy that your body can use.

12 Potential Energy (cont.) The energy stored in and released from the nucleus of an atom is called nuclear energy. The Sun s energy is released through the process of nuclear fusion, during which the nuclei of atoms join together and release large amounts of energy.

13 Kinetic Energy Kinetic energy is energy due to motion. An object s kinetic energy is related to the mass and the speed of the object. The energy in an electric current is electric energy.

14 Kinetic Energy (cont.) How do potential energy and kinetic energy differ?

15 Combined Kinetic Energy and Potential Energy The sum of the potential energy and the kinetic energy in a system is mechanical energy. mechanical from Greek mēchanē, means machine

16 Combined Kinetic Energy and Potential Energy (cont.) An object s thermal energy is the sum of the kinetic energy and the potential energy of the particles that make up the object. Thermal energy of an object increases when the potential energy, the kinetic energy, or both increase.

17 Combined Kinetic Energy and Potential Energy (cont.) Compare mechanical energy and thermal energy.

18 Energy Carried by Waves A wave is a disturbance that transfers energy from one place to another without transferring matter. Sound energy is carried by sound waves. The energy carried by electromagnetic waves is radiant energy.

19 Electromagnetic waves often are described by their wavelengths the distance from one point on a wave to the nearest point just like it.

20 Visible light is one form of radiant energy.

21 Energy Carried by Waves (cont.) What two forms of energy are carried by waves?

22 Objects can have potential energy (stored energy) and kinetic energy (energy due to movement). Mechanical energy is due to largescale motions and interactions in a system. Thermal energy is due to atomic-scale motions and interactions in particles.

23 Two kinds of energy carried by waves are sound energy and radiant energy.

24 Which term describes energy stored in and released from the bonds between atoms? A. chemical energy B. kinetic energy C. mechanical energy D. nuclear energy

25 Which refers to a disturbance that transfers energy from one place to another without transferring matter? A. wave B. wavelength C. potential energy D. thermal energy

26 What type of energy provides the warmth from the Sun? A. chemical energy B. nuclear energy C. potential energy D. radiant energy

27 Do you agree or disagree? 1. An object sitting on a high shelf has no energy. 2. There are many forms of energy.

28 Energy Transfers and Transformations What is the law of conservation of energy? How is energy transformed and transferred? What are renewable and nonrenewable energy resources?

29 Energy Transfers and Transformations law of conservation of energy energy transfer energy transformation work open system closed system renewable energy resource nonrenewable energy resource

30 Law of Conservation of Energy The law of conservation of energy says that energy can be transformed from one form to another, but it cannot be created or destroyed.

31 The law of conservation of energy indicates that the amount of radiant energy that shines out of the flashlight cannot be greater than the chemical energy stored in the battery.

32 Law of Conservation of Energy (cont.) What is the law of conservation of energy?

33 Law of Conservation of Energy (cont.) When energy moves from one object to another without changing form, an energy transfer occurs. The mechanical energy of a tennis racket changing the movement of the ball is an example of an energy transfer.

34 Law of Conservation of Energy (cont.) When one form of energy is converted to another form of energy, an energy transformation occurs. The conversion of chemical energy stored in a tennis player s muscle changing to mechanical energy when she swings her arm is an example of an energy transformation.

35 Law of Conservation of Energy (cont.) Identify an energy transfer and an energy transformation that occurs when someone plays a guitar.

36 Law of Conservation of Energy (cont.) To a scientist, work is the transfer of energy that occurs when a force makes an object move in the direction of the force. Work is only being done while the force is acting on the object. Any time there is an energy transformation or energy transfer, some energy is transformed into thermal energy.

37 Law of Conservation of Energy (cont.) Because energy transformations are inefficient, some of the chemical energy transforms to thermal energy and sound energy that are released to the environment. An open system is a system that exchanges matter or energy with the environment.

38 Law of Conservation of Energy (cont.) A closed system is a system that does not exchange matter or energy with the environment. In reality, there are no closed systems because every physical system transfers some energy to or from its environment.

39 Law of Conservation of Energy (cont.) system from Greek systema, means whole made of several parts

40 Energy Transformations and Electric Energy A renewable energy resource is an energy resource that is replaced as fast as, or faster than, it is used. Solar energy from the Sun is one type of renewable energy resource that can be converted into electric energy.

41 Energy Transformations and Electric Energy (cont.) Wind moves the blades of a wind turbine to generate electric energy. In hydroelectric plants, falling water is channeled through a turbine which transforms mechanical energy into electric energy.

42 Energy Transformations and Electric Energy (cont.) Geothermal plants transfer thermal energy from the Earth to water, creating steam that turns turbines in electric generators. Biomass includes wood, plants, manure, and garbage, all of which are sources of stored chemical energy that can be transformed to electric energy in energy plants.

43 Energy Transformations and Electric Energy (cont.) Nonrenewable energy resources are energy resources that are available in limited amounts or that are used faster than they can be replaced in nature. Fossil fuels include petroleum, natural gas, propane and coal. In nuclear energy plants, uranium atoms are split apart in a process called nuclear fission.

44 Most of the energy used in the United States comes from nonrenewable energy resources.

45 Energy Transformations and Electric Energy (cont.) What are renewable and nonrenewable energy resources?

46 Energy can be transferred and transformed, but it cannot be created or destroyed. Systems are classified as open systems or closed systems based on their interactions with their environment. Energy resources are classified as renewable or nonrenewable based on their abundance and availability.

47 Which term refers the transfer of energy that occurs when a force makes an object move in the direction of the force? A. conservation B. work C. closed system D. open system

48 A car s engine is an example of which of these? A. closed system B. energy resource C. geothermal energy D. open system

49 Which is an example of biomass? A. open system B. solar energy C. nonrenewable energy resource D. renewable energy resource

50 Do you agree or disagree? 3. In most systems, no energy is transferred to the environment. 4. Some forms of energy are replenished naturally.

51 Particles in Motion What is the kinetic molecular theory? In what three ways is thermal energy transferred? How are thermal conductors and insulators different?

52 Particles in Motion temperature heat conduction radiation convection vaporization thermal conductor thermal insulator

53 Kinetic Molecular Theory The kinetic molecular theory explains how particles move and has three major points: All matter is made of particles. Particles are in constant, random motion. Particles constantly collide with each other and with the walls of their container.

54 Particles that make up all matter are in constant motion. On average, solid particles move slowest, liquid particles move faster, and gas particles move the fastest.

55 Kinetic Molecular Theory (cont.) What are the three points of the kinetic molecular theory?

56 Kinetic Molecular Theory (cont.) The measure of the average kinetic energy of the particles in a material is temperature. When the particles that make up a material move slowly, they occupy less volume than they do at a higher temperature. Thermal expansion is the increase in volume of a material due to a temperature increase.

57 Kinetic Molecular Theory (cont.) When water is cooled to near its freezing point, interactions between water molecules push the molecules apart.

58 Kinetic Molecular Theory (cont.) As the kinetic energy of the particles that make up a material increases, the thermal energy of the particles increases. As the kinetic energy of the particles that make up a material decreases, the thermal energy of the particles decreases.

59 When you put a warm bottle of water in a cold refrigerator, thermal energy is transferred.

60 Kinetic Molecular Theory (cont.) The movement of thermal energy from a region of higher temperature to a region of lower temperature is called heat. When the temperatures of materials that are in contact are the same, the materials are said to be in thermal equilibrium.

61 Kinetic Molecular Theory (cont.) equilibrium from Latin aequus, means equal ; and libra, means a balance or scale

62 Heat Transfer Conduction is the transfer of thermal energy by collisions between particles in matter. Radiation is the transfer of thermal energy by electromagnetic waves. Convection is the transfer of thermal energy by the movement of the particles from one part of a material to another.

63 Conduction, radiation, and convection are ways in which thermal energy is transferred.

64 Heat Transfer (cont.) In what three ways is thermal energy transferred?

65 Heat and Changes of State Melting is the change of state from a solid to a liquid. Freezing is the change of state from a liquid to a solid.

66 Heat and Changes of State (cont.) Vaporization is the change of state from a liquid to a gas. Vaporization that occurs within a liquid is called boiling. Vaporization that occurs at the surface of a liquid is called evaporation.

67 Heat and Changes of State (cont.) Sublimation is the change of state that occurs when a solid changes to a gas without passing through the liquid state. Deposition is the change of state from a gas directly to a solid without passing through the liquid state. Water vapor undergoes deposition when it freezes and forms frost.

68 Heat and Changes of State (cont.) sublime Science Use to change from a solid state to a gas state without passing through the liquid state Common Use inspiring awe; supreme, outstanding, or lofty in thought or language

69 Conductors and Insulators A thermal conductor is a material in which thermal energy moves quickly. A thermal insulator is a material in which thermal energy moves slowly.

70 Conductors and Insulators (cont.) How do thermal conductors differ from thermal insulator?

71 The kinetic molecular theory explains how particles move in matter.

72 Thermal energy is transferred in various ways by particles and waves. Materials vary in how well they conduct thermal energy.

73 Which term refers to the transfer of thermal energy between particles in matter? A. conduction B. convection C. heat D. radiation

74 Which describes the transfer of thermal energy by the movement of particles from one part of a material to another? A. conduction B. convection C. radiation D. vaporization

75 What is the change of state from a gas directly to a solid without passing through the liquid state? A. deposition B. melting C. sublimation D. vaporization

76 Do you agree or disagree? 5. Only particles that make up moving objects are in motion. 6. Thermal energy can be transferred in several ways.

77 Key Concept Summary Interactive Concept Map Chapter Review Standardized Test Practice

78 Energy is involved in all physical processes; it is transferred when it moves from object to object without changing form. Energy is transformed when it is converted to another form. Energy is conserved during transfers and transformations.

79 Lesson 1: Forms of Energy Potential energy is stored energy, and kinetic energy is energy of motion. Both mechanical energy and thermal energy involve kinetic energy and potential energy. Mechanical energy is the sum of the kinetic energy and the potential energy in a system of objects. Thermal energy is the sum of the kinetic energy and the potential energy in a system of particles. Sound energy and radiant energy are carried by waves.

80 Lesson 2: Energy Transfers and Transformations The law of conservation of energy says that energy can be transformed from one form to another, but it cannot be created or destroyed. Energy is transformed when it is converted from one form to another. It is transferred when it moves from one object to another. Renewable energy resources are resources that are replaced as fast as, or faster than they are used. Nonrenewable energy resources are resources that are available in limited quantities or are used faster than they can be replaced.

81 Lesson 3: Particles in Motion The kinetic molecular theory says that all objects are made of particles; all particles are in constant, random motion; and the particles collide with each other and with the walls of their container. Thermal energy is transferred by conduction, radiation, and convection. A thermal conductor transfers thermal energy easily and a thermal insulator does not transfer thermal energy easily.

82 Which describes the sum of the potential energy and the kinetic energy in a system? A. mechanical energy B. nuclear energy C. sound energy D. thermal energy

83 Which refers to energy due to motion? A. electric energy B. kinetic energy C. potential energy D. radiant energy

84 Which term refers to an energy resource that is replaced as fast as, or faster than, it is used? A. fossil fuel B. natural gas C. nonrenewable energy resource D. renewable energy resource

85 Which term refers to a system that exchanges matter or energy with the environment? A. closed system B. energy resource C. open system D. solar energy

86 Which refers to the movement of thermal energy from a region of higher temperature to a region of lower temperature? A. conduction B. deposition C. heat D. vaporization

87 Which term refers to the ability to cause change? A. energy B. heat C. wave D. work

88 If an object has mass and height above Earth s surface, what type of energy does it have? A. gravitational potential energy B. kinetic energy C. nuclear energy D. radiant energy

89 What type of energy is stored in and released from the nucleus of an atom? A. chemical energy B. nuclear energy C. radiant energy D. thermal energy

90 Which term refers to energy resources that are available in limited amounts or that are used faster than they can be replaced in nature? A. energy transfer B. solar energy C. nonrenewable energy resources D. renewable energy resources

91 Which is a material in which thermal energy moves slowly? A. radiation B. kinetic energy C. thermal conductor D. thermal insulator