1. Energy Forms and Conversions
Chapter 16:
Energy Forms and Conversions

2. Before we move on,
We have…
Representing the video clip available

3. Lesson Outline state what is meant by energy
                                      
                                        
Lesson Outline
state what is meant by energy
describe different forms of energy and how energy changes from one form to another
infer that energy is conserved and can be transformed from one form to another
appreciate the need for Singapore – which has no natural resources of her own – to conserve energy

4. Different forms of energy
Potential
Gravitational
Chemical
Elastic
Kinetic
Light
Sound
Heat
Electrical
Nuclear 4

5. 16.1 Energy and Its Various Forms
                                      
16.1 Energy and Its Various Forms
Energy is the ability to do work.
There are different forms of energy:
chemical
potential
kinetic
Energy types
light
nuclear
heat
sound
Which is potential and which is kinetic
electrical
You make use of different types of energy to help you do work in your daily life.

6. Lesson Outline state what is meant by energy
                                      
                                        
Lesson Outline
state what is meant by energy
describe different forms of energy and how energy changes from one form to another
infer that energy is conserved and can be transformed from one form to another
appreciate the need for Singapore – which has no natural resources of her own – to conserve energy

7. Chemical potential energy
                                      
(a) Potential Energy
Potential energy is a form of stored energy.
Gravitational potential energy
Chemical potential energy
Elastic potential energy
Potential energy
Gravitational
potential energy
Chemical potential energy
Elastic
potential energy

8. Gravitational Potential energy8

9. Gravitational force
The earth is kept in it’s orbit by the sun’s gravitational pull
Sun
Earth

10. (1) Gravitational potential energy
The airplane's stored energy is due to its elevated position in a region where there is gravity. This type of potential energy is called gravitational potential energy.

11. Gravitational Potential Energy
If two objects have the same mass but are at different heights, the one with the greater height will have more gravitational potential energy.

12. Gravitational Potential Energy
If two objects are at the same height from the ground, the one with the greater mass will have more gravitational potential energy.

13. The formula for Gravitational Potential Energy
G.P.E = Mass x Gravity x Height
G.P.E = mgh

14. Elastic Potential Energy
Show video of mouse trap
Elastic Potential Energy 14

15. (2) Elastic potential energy
This is found in stretched or compressed elastic objects (e.g., compressed spring)
Which equipment make use of a spring to work?

16. Elastic Potential Energy
Elastic potential energy is the energy stored in an elastic object when it is pushed or pulled.
When an elastic object is pushed or pulled, it stores energy which can be released to do work.

17. (3) Chemical potential energy
The stored energy in the food is called chemical potential energy.
Chemical energy is the energy which holds the atoms and molecules of substances together.
This stored energy is released during chemical reactions.
What is the name of chemical reaction/s that release energy in
the body?
the fuels?

18. Chemical Potential Energy
What energy is stored in burning wood?
Which process releases the stored energy in wood?
In what forms is the stored energy in the wood released? 18

19. It is found in fuels, food, batteries and in living things
It is found in fuels, food, batteries and in living things. It is only released when a chemical reaction takes place.

20. Summary of Potential Energy
Potential energy is stored energy in a body as a result of its position or condition
3 types of potential energy
Gravitational
Elastic
Chemical

21. Kinetic Energy

22. (b) Kinetic energy
Kinetic Energy is the energy of a body due to its motion.
The amount of the energy is directly proportional to the mass of an object.
Why cars and bullets can cause damage at high speeds?

23. Moving objects possess kinetic energy
Kinetic energy is the energy that a body possesses due to its motion.
Moving objects possess kinetic energy

24. Kinetic Energy
If two objects have the same mass but are moving at different speeds, the one with the greater speed will have more kinetic energy.

25. Kinetic Energy
The greater the mass of a moving object, the greater its kinetic energy.

26. Formula for Kinetic Energy
K.E = (1/2)(mass)(velocity)2
K.E = (1/2)mv2

27. Light Energy

28. (c) Light energy
Light is a form of energy that allows us to see things and for plants to make food.
What is this chemical process?
Optical fibres also make use of light to transmit huge amounts of information over long distances at high speeds. ??
Did You Know
An optical fibre is a glass or plastic fibre designed to guide light along its length.

29. Light Energy Light is a form of energy which enables us to see.
A light source produces its own light.
The Sun is our main source of light.

30. Sound Energy
Sound is a form of energy produced by vibrations which can be detected by our ears.
A loud sound carries more energy than a soft sound.
Your voice is produced when the vocal cords in your voice box vibrates. Unlike the vibrations of a string, the vibrations of some objects are not so easily observed.

31. Sound Energy Sound can travel through solid liquid gas
Show video on sound in vacuum
But cannot travel through vacuum. 31

32. Sound energy Loud sounds and noise cause sound pollution.
Sounds produced by musical instruments are pleasant to our ears.

33. Electrical Energy
Electrical energy is a form of energy made available by the flow of electric charges such as electrons and ions.
Electric cells and power points are the main sources of electrical energy.
The electrical energy from
power points comes from
power stations.

34. Electrical Energy
It is widely used as it can be easily generated and transmitted over long distances and be converted into other forms of energy to do work.
Can you name examples in the classroom?

35. Heat Energy

36. Heat Energy
It is a form of energy comes from the internal motion of the particles in a body;
Heat is a form of energy which flows from a region of higher temperature to a region of lower temperature.
The Sun is our main source of heat.
This shows that heat can travel through VACUUM.
It can travel through solids, liquids, gases and vacuum.
We can obtain a large amount of heat from burning fuels.

37. Nuclear power stations produce electrical energy for use.
Nuclear energy when misused, can be harmful.
Nuclear Energy 37

38. (g) Nuclear energy
It is a form of energy that comes from a nuclear reaction. Two types of nuclear reaction:
- Nuclear fusion: Large amount of energy is released when nuclei of small atoms combine to form heavier ones.
(e.g., energy of the Sun)
- Nuclear fission: Energy is produced when the nucleus of a heavy atom is split into smaller ones. (e.g., nuclear power stations)
It can be disastrous if it is abused.
(e.g., nuclear bombs used in World War II)

39. A nuclear accident at a nuclear power plant in Chernobyl, Ukraine, in 1986 killed thousands of people. Many of them suffered from cancers caused by exposure to the harmful radiation released.
Chernobyl Disaster
Sun energy is produced when small atoms combine to form heavier ones.
Nuclear energy from power stations is produced when a heavy atom is split into smaller ones.
Nuclear energy can be disastrous is abused or released without proper control.

40. Clarification Work is the transfer of energy. Calculation of Energy
SI unit of Energy : Joule (J)

41. K.E. = ½ mv2
where m is the mass and v is the velocity of the object
Gravitational P.E. = mgh
where m is the mass, g is gravitational force and h is the height of the object

42. A man of mass 80 kg is moving at a speed of 2. 0 m/s
A man of mass 80 kg is moving at a speed of 2.0 m/s. Calculate the kinetic energy of the man.

43. Clarification KE = ½ mv2 = ½ x 80 x 2.02 = 160 J
Gravitational P.E. = mgh
where m is the mass, g is gravitational force and h is the height of the object
An apple of mass 0.10 kg at the height of 2.0 m on a tree. Calculate the P.E. of the apple.

44. Definition of energy: ________________________________________________________________________________________________ The seven forms of energy are __________________________________________________________________________

45. Objects which have a greater____________ or are at a greater___________ possess more kinetic energy.
Objects which have a greater ____________ or are at a greater ____________ possess more gravitational potential energy.
The two sources of electrical energy are the _____________ and _____________.

46. Definition of energy: The ability to do work
Definition of energy: The ability to do work. The seven forms of energy are: Potential, Kinetic, Light, Sound, Heat, Electrical, Nuclear

47. Objects which have a greater___mass___ or are at a greater__speed__ possess more kinetic energy.
Objects which have a greater ___mass___ or are at a greater __height___ possess more gravitational potential energy.
The two sources of electrical energy are the __battery/electric cells___ and ___powerpoint___.

48. car being pulled up by electrical winch
gravitational potential energy
mechanical energy (potential energy + kinetic energy)
electrical energy
car being pulled up by electrical winch
Electrical energy  Gravitational potential energy
 Mechanical energy + Heat energy

49. Lesson Outline state what is meant by energy
                                      
                                        
Lesson Outline
state what is meant by energy
describe different forms of energy and how energy changes from one form to another
infer that energy is conserved and can be transformed from one form to another
appreciate the need for Singapore – which has no natural resources of her own – to conserve energy

50.                                       
                                        
16.2 Conversion of Energy
The energy is converted from one form to another when work is done.
For e.g.,
Solar panels capture light energy from the Sun, and convert it to electricity.
Green plants undergo photosynthesis to convert light energy into chemical energy in the form of food.

51. Conversion of Energy
Potential energy of the book at a greater height change to kinetic energy as the book falls.
PE decreases while KE increases.

52. Conversion of Energy
Chemical Energy stored in the body is converted to kinetic energy as the body is moving.
Kinetic Energy is then converted to Potential Energy as the body gains height.

53. Conversion of Energy
The car engine allows the stored chemical energy of gasoline to be transformed into mechanical energy that drives the wheels of the car. 

54. Conversion of Energy
Electrical Energy convert to light and thermal energy as the electrical light bulb lights up.

55. Conversion of Energy
Light Energy from the sun converted to Electrical Energy in a solar panel.

56. Conversion of Energy
Wind mills make use of the kinetic energy of the air molecules, transforming it to mechanical or electrical energy.

57. Conversion of Energy
Hydroelectric plants transform the kinetic energy of falling water into electrical energy.

58. Rubbing your hands together
Kinetic Energy  Sound Energy + Heat Energy
Shaking a bottle of beans
Kinetic Energy  Sound Energy

59. Burning Wood
Chemical Potential Energy  Heat Energy + Light Energy

60. Singing into a microphone
Sound Energy  Electrical Energy

61. Plants Photosynthesizing
Light Energy  Chemical Potential Energy

62. Pole Vaulting
Kinetic Energy  Elastic Potential Energy  Gravitational Potential Energy  Kinetic Energy
video 62

63. Pendulum Bob Z X Y Lowest kinetic energy Highest potential energy
Highest kinetic energy
Lowest potential energy

64. Energy is conserved The conservation of energy states that
energy cannot be created or destroyed but
energy can change from one form into another.
USEFUL ENERGY
(USED TO DO WORK) =
TOTAL
TOTAL
Kinetic energy
Potential energy
+ Heat energy + Sound energy
WASTED ENERGY

65. Laws of Conservation of Energy
                                      
                                        
Laws of Conservation of Energy
In any closed system, the total amount of energy remains constant before and after work is done, regardless of any process taking place.
When more work is done, more energy is converted.
Energy cannot be created nor destroyed. It can be converted from one form into another, and each time, work is always done.

66. By the Law of conservation of energy
Total energy at A =Total energy at B=Total energy at C
( PEA ) = ( PEB + KEB ) = ( KEC )
mg(x+n) = mgn + 1/2 mvB2 = 1/2 mvmax2 x n A B C
PEA (at rest)
KE=0
PEB
KEB
KEC
PE=0

67. The law of conservation of energy states that (i)___________________________________ (ii)___________________________________

68. Energy conversion for a toaster:
________________

69. Light energy is converted to chemical potential energy in a ________________.
Chemical potential energy is converted to electrical energy in a ________________.
We cannot hear sound in a _______________.

70. The law of conservation of energy states that
energy cannot be created or destroyed but
energy can change from one form into another.

71. Energy conversion for a toaster:
Electrical energy  Heat and Light energy

72. Light energy is converted to chemical potential energy in a plant.
Chemical potential energy is converted to electrical energy in a power station.
We cannot hear sound in a vacuum.

73. How is electrical energy produced?
A power station uses fossil fuels such as coal, natural gas and oil.
When these fossil fuels are burnt, the chemical energy stored in these fuels is released to boil water to form steam.
The moving steam turns the turbines which turns the generator.
When the generator turns, electrical energy is produced.
The energy conversions
in the power station :
chemical energy  heat energy 
kinetic energy  electrical energy

74. Non Renewable Sources of Energy
Oil drilling rig
These fossil fuels pollute the environment when they are burnt.
They are limited, i.e. they will run out.
Coal mine

75. Non Renewable sources of energy
These alternative sources of energy are clean (pollution free) and do not run out.
However, they are expensive or unsuitable to harness in some places.

76. Wind energy A wind turbine uses energy from wind to turn the turbines.
Need a large area of land

77. Solar panels A solar panel uses heat from the sun.
Expensive and need hot climate
Solar panels

78. Solar cells

79. Geothermal Power A geothermal power plant uses heat from the earth.
video
A geothermal power plant uses heat from the earth.
Expensive to install 79

80. Biomass Energy
Fuels such as biogas and alcohol are derived from biomass (plant materials or wastes from living things)
Take up valuable fertile land.
Need the correct climate

81. Hydroelectricity Power
Requires mountainous areas
video
A hydroelectric power station uses energy from falling water. 81

82. Wave energy
Interfere with shipping
Expensive

83. Tidal energy
Few places are suitable
Expensive

84. The Future
Science tells us we must turn towards energy sources that are:
- renewable;
- sustainable;
- less polluting.
We need to learn how to use energy more
efficiently and responsibly.

85. Hey! Why are you running so slowly?
Conserving Energy
We’ve only run 1 km of the marathon. I’m conserving energy for the rest of the race!
Hey! Why are you running so slowly?

86. Singapore has no natural resources, it has to depend on IMPORTED fossil fuels to meet its energy needs.
Hence, it is very important for us to conserve energy by:
Developing and using energy efficient devices. (use fluorescent lamps instead of filament lamps)
Recycling and reusing materials
Use public transport system
Switch off electrical appliances when not using them
Conserving Energy

87. Saving Energy
Inverter air-con
Developing and using energy-efficient devices and processes
Reducing wastage of energy
Recycling and reusing materials
Using more efficient public transportation systems
Saving and optimising the use of electricity

88. Fossil fuels is a form of _________________ source of energy.
The two disadvantages of using fossil fuels as a form of energy are that ________________
_____________________________________.

89. Examples of fossil fuels are _________________________
Examples of fossil fuels are _________________________. The form of energy stored in fossil fuels is ________________ energy. The seven types of renewable sources of energy are ______________________________________________________________________________ The energy conversion in power stations (fossil fuels): ___________________________

90. Fossil fuels is a form of non-renewable source of energy.
The two disadvantages of using fossil fuels as a form of energy are that they pollute the environment and they are limited/will run out.

91. Examples of fossil fuels are coal, oil and natural gas
Examples of fossil fuels are coal, oil and natural gas. The form of energy stored in fossil fuels is chemical potential energy. The seven types of renewable sources of energy are wind, tidal, waves, hydroelectricity, biomass, geothermal and solar. The energy conversion in power stations (fossil fuels): chemical energy  heat energy  kinetic energy  electrical energy.