Chapter 6

CHAPTER 6:SOURCE OF ENERGY

Prepared by:

LEE HOCK TIANG

6.1 THE VARIOUS FORMS AND SOURCES OF ENERGY

6.1.1 Forms of Energy1. Energy is the ability to carry out work.2. All living things need energy to carry out

daily activities.3. Energy enables us to talk, walk and breathe.4. We obtain energy from our food.5. Vehicles and machines need energy to

move and function.6. We can get energy in various forms. There

are two main types of energy, i.e. stored energy and working energy.

Various forms or energy

Stored energy Potential energy Chemical energy Nuclear energy

Working energy Heat energy Kinetic energy Light energy Electrical

energy Sound energy

POTENTIAL ENERGY

1. Potential energy is the energy possessed by an object as a result of its position or condition.

2. It is an energy stored in an object that is:a) Raised up high above the surface of the

Earthb) Compressed or stretched3. The height of an object from the surface of

the Earth and the mass of the object influence the total potential energy stored in the object.

4. The further an object is from the surface of the Earth, the higher its potential energy.

EXAMPLES OF SITUATIONS THAT INVOLVE POTENTIAL ENERGY

1. Water at the top of a waterfall2. Water accumulated in a dam3. A compressed spring4. A fruit hanging on a tree

SOME APPLICATIONS OF POTENTIAL ENERGY

1. Potential energy stored in water is used to move the turbine in a hydroelectric power station.

2. A compressed or stretched spring has potential energy to rotate the needle of a clock.

3. The stretched rubber band of a catapult has potential energy to release the stone.

KINETIC ENERGY

1. Kinetic energy is the energy possessed by a moving object.

2. An object has greater kinetic energy when it has a greater speed of motion.

3. Examples of situations that involve kinetic energy:

a) Blowing wingb) Moving cars or vehiclesc) A man runningd) Flowing water

SOME APPLICATIONS OF KINETIC ENERGY:

1. In the logging industry, kinetic energy from flowing water in the river is used to carry logs from the forest to the sawmill.

2. Kinetic energy from wind can rotate the blades of windmills to generate electrical energy and to move a yacht.

3. Waves have kinetic energy which can be used to rotate a dynamo to generate electrical energy.

4. Kinetic energy from jets of water is used in tin mining.

LIGHT ENERGY

1. Light energy is obtained from objects that produce light.

2. Light energy can be detected by the eyes.3. Some sources of light energy.a) The Sunb) Flame from a burning objectc) Glowing light bulbd) Lightninge) Chemical reactions4. The light energy that reaches the Earth

originates from the Sun.

SOME APPLICATIONS OF LIGHT ENERGY:

1. Sight mechanism in humans2. Photosynthesis process in green plants3. Controlling traffic with traffic lights4. Solar cells absorbing sunlight which is then

converted into electrical energy5. Video and film shows6. Cameras and photostating machines

HEAT ENERGY

1. Heat energy is the energy that brings about a rise in the temperature of an object.

2. A burning material releases heat energy.3. Heat energy flows from an area of higher

temperature to an area of lower temperature.

4. Some sources of heat energy:a) The Sunb) Firec) Burning fueld) Electrical applications

SOME APPLICATIONS OF HEAT ENERGY:

1. Keeping the body warm2. Heating water and cooking food3. Drying wet clothes4. Preserving food5. Turning turbine to generate electrical

energy

SOUND ENERGY

1. Sound energy is produced through the vibration of objects.

2. Sound energy moves through air particles in the form od waves.

3. Sound energy that is produced by vibrating objects can be detected by ears.

4. Sound energy can be transferred through solids, liquids and gases but not through a vacuum.

5. Some source of sources of sound energy:a) Voices of man and animalsb) Thunderc) Sound-producing objects such as bells, ticking

clocks, and horns of vehicles d) Musical instrumentse) Waves

SOME APPLICATIONS OF SOUND ENERGY:

1. Man can communicate with one another.2. Warning equipment such as sirens from

ambulances and police cars can function.3. Music and songs can be enjoyed as a form

of entertainment.

ELECTRICAL ENERGY

1. Electrical energy is produced by moving charges or electric current.

2. Some sources of electrical energy are the dynamo, electrical generator, battery and lightning.

3. Some applications of electrical energy:a) To light a bulbb) To turn on a television and a computerc) To turn on an electric kettle or other

electrical appliance

MECHANICAL ENERGY

1. Mechanical energy is made up of kinetic energy and potential energy

2. Mechanical energy is produced by machines and objects which change their positions.

3. This energy is also called energy of motion.4. Some examples of mechanical energy:a) An operating machine such as the rotating

blades of a fanb) The rotating wheels of a vehiclec) The oscillation of a simple pendulumd) The board of a seesaw which is moving up and

downe) The rocking of a cradle

CHEMICAL ENERGY

1. Chemical energy is the energy stored in chemical substances such as food and fuel.

2. Chemical energy is released when an object undergoes chemical reaction or when it is burnt.

3. Chemical energy can change to heat, light, sound and electrical energy.

4. The chemical energy stored in food is released when the food is oxidized in the body to provide heat energy.

5. In a dry cell, the chemical energy stored is converted into electrical energy.

6. When fuels such as natural gas, charcoal, petrol and alcohol are burnt, the stored chemical energy is released in the form of light and heat energy.

SOME APPLICATIONS OF CHEMICAL ENERGY:

1. Chemical energy in the battery produces electrical energy for electrical equipments to function.

2. Production of mechanical energy to move egines of vehicles and machines.

3. Chemical energy in food produces heat energy to keep the body warm.

NUCLEAR ENERGY

1. Nuclear energy is stored in the nucleus of an atom.

2. Two types of nuclear reactions that release nuclear energy:

a) Nuclear fusion is the combination of two small atoms to produce a bigger atom.

b) Nuclear fission is the splitting up of an atom to form smaller atoms.

3. Nuclear energy released during nuclear fusin and fission exists in the form of heat, light and sound energy or in the form of hazardous radiation.

SOME APPLICATIONS OF NUCLEAR ENERGY:

1. To produce electrical energy in nuclear-generating stations.

2. To produce atomic and hydrogen bombs.3. To move nuclear submarines.

6.1.2 SOURCES OF ENERGY

Some examples of energy sources:1. The Sun2. Biomass3. Wind4. Water5. Fossil fuels6. Waves and tides7. Geothermal sources8. Radioactive substances

THE SUN

1. The Sun gives out solar energy.2. Solar energy is used by green plants to

carry out photosynthesis.3. Solar energy can be converted into heat

and electrical energy.

BIOMASS

1. Plant and animal waste can be burnt to produce biomass energy.

2. Decomposition of plant and animal wastes by bacteria produces carbon dioxide and biomass fuels such as alcohol and biogas.

3. Biomass energy is used to produce:a) Steam to warm housesb) Electrical energy by driving turbines and

dynamos4. In Malaysia, methane gas is generated in

tanks as fuel by decomposing organic wastes from rubber estates and palm oil plantations.

WIND

1. Wind moves from a cooler place to a warmer place and wind possesses kinetic energy.

2. Uneven heating of the surface of the surface of the Earth by the Sun creates wind.

3. Some applications of wind energy:a) To move a windmillb) To move a sailing boatc) To move wind turbines and dynamos to

produce electrical energy

WATER

1. A dam can block water in a river.2. Potential energy is stored in the water in the

dam. When the water flows out, it has kinetic energy.

3. Turbines in a hydroelectric power station are turned by kinetic energy from the flowing water.

FOSSIL FUELS

1. Coal, natural gas and petroleum are fossil fuels. These fossil fuels were formed from the remains of plants and animals buried in the Earth millions of years ago.

2. Fossil fuels are widely used nowadays especially to move vehicles.

3. Some uses of fossil fuels:a) Coal – to warm houses in cold countriesb) Natural gas – to cook foodc) Petroleum (petrol, diesel, kerosene) – to

move vehicles and engines

WAVES AND TIDES

1. Waves have potential energy and kinetic energy.

2. Waves are produced when wind blows on the surface of the sea.

3. High and low tides occur due to the gravitational pull of the Moon towards the sea water.

4. Tides are used to rotate turbines to generate electrical energy.

GEOTHERMAL SOURCES

1. We obtain geothermal energy from the inside of the Earth as heat energy.

2. The inside of the Earth is very hot and some of the heat energy of hot springs, geysers and volcanoes come out through eruptions.

3. Steam from geysers is used to generate electrical energy.

4. Geothermal energy is converted into electrical energy.

RADIOACTIVE SUBSTANCES

1. The splitting of the atoms of uranium or plutonium in a controlled way in reactor produces nuclear energy.

2. Some uses of nuclear energy:a) To drive turbines and dynamos to produce

electrical energyb) To drive propellers which move submarines

6.1.3 THE SUN AS THE PRIMARY SOURCE OF ENERGY

1. The Sun is the primary source of energy on Earth.

2. The Sun gives out direct energy to the Earth as heat and light energy.

3. Nuclear fusion occurs in the Sun as hydrogen atoms combine to form helium atoms and release a large amount of heat and light energy.

4. All living things depend on energy from the Sun.

SOME OF THE EXAMPLES ARE AS FOLLOW:

a) Green plants can make food through photosynthesis.

b) Human beings can carry out their daily activities.

c) The food chain is affected if plants do not carry out photosynthesis.

d) Energy for operating appliances such as solar calculators and solar heaters is obtained from solar energy.

All energy on the Earth has direct or indirect relation with the Sun as the Sun is the primary source of energy.a) Green plants absorb sunlight to carry out

photosynthesis.b) Energy stored by plants is kept in the form of

chemical energy.c) When plants are eaten by animals, the

chemical energy of the plants is transferred to their bodies.

d) Organic substances of dead plants and animals become fossil fuels after millions of years.

e) When land and sea are heated by the Sun, wind is produced. When wind blows on the surface of the sea, waves are produced.

6.1.4 ENERGY CHANGES

1. The Principle of Conservation of Energy states that:

a) Energy cannot be created or destroyedb) Energy can be changed from one form to

another2. Energy is conserved because:Total energy before change = Total energy after change

3. Some energy may be wasted as heat energy.4. Energy changes from one from to another.5. Converters are used to change energy from

one to another.

SOME EXAMPLES OF ACTIVITIES AND THE ENERGY CHANGES

INVOLVEDRubbing the palms of both hands.Friction sound is heard and the palms of both hands are warm.

Kinetic energy Heat energy + Sound energy(movement of (the palms of (friction sound) hands) the hands become warm)


INVOLVEDSwitching on a torchlightLight is produced and the glass of the torchlight becomes hot.

Chemical Electrical + Light + Heat energy energy energy energy (energy stored (current flow (bulb is (the glassin the battery in the circuit) lighted) area of theof the torchlight) torchlight become hot)


INVOLVEDPlucking guitar stringsThe sound of the guitar is heard.

Potential energy Kinetic energy + Sound energy(the guitar strings (the strings of (sound of theAre stretched when the guitar vibrate) guitar)They are plucked)


INVOLVEDTossing a ball upwards

The ball reaches a maximum height and falls to the floor.

Kinetic Potential + Kinetic + SoundEnergy energy energy energy(the ball (the energy (the ball (when theMoves stored in the moves ball hits upwards) ball because downwards) the floor) of its height)

6.2.1 RENEWABLE AND NON-RENEWABLE SOURCES OF

ENERGY

1. Energy sources can be divided into two types:

a) Renewable energy sourcesb) Non-renewable energy sources2. Renewable energy sources are energy

sources that always exist and cannot be depleted even if they are used constantly.

3. Non-renewable energy sources are energy sources that can be depleted and cannot last forever.

4. We can group the various sources of energy into renewable and non-renewable.

RENEWABLE ENERGY SOURCES

1. The Sun2. Wind3. Biomass4. Water 5. Tidal waves6. geothermal

NON-RENEWABLE ENERGY SOURCES

1. Fossil fuels a) Natural gasb) Petroleumc) Coal2. Radioactive substances

RENEWABLE SOURCES OF ENERGY

THE SUN1. Solar energy is energy from the Sun and it is a clean

and non-polluting source of energy.2. Nuclear reactions that occur in the Sun produce heat

and light energy.3. Although energy from the Sun can be obtained easily

on the Earth, it is very weak.4. Solar-heated equipments absorb light energy from the

Sun. The accumulated sunlight turns to heat energy to heat up water and cook food.

5. A solar cell is an equipment used to turn solar energy to electrical energy as seen in calculators and satellites.

6. This solar energy has its disadvantages as it is dependent on weather and the cost of making devices to collect the energy is high.


WIND1. Moving air is called wind.2. Wind is formed when the Earth is heated by the

Sun and this makes different parts of the Earth’s surface heated unequally.

3. Air which is closest to the surface of the Earth becomes hot and expands. This air rises to the top.

4. Cold air which is denser moves into the space vacated by the hot air. This cold air which moves fast is wind.

5. Wind is also used to move yachts, rotate windmills, operate machines and pump water into agricultural areas.


BIOMASS1. Biomass energy is obtained from the

decaying process of organic waste matter.2. The chemical energy stored in the biomass

fuel is formed during decomposition of animal and plant waste.

3. To produce sufficient amount of energy, a large amount of organic wastes is required.


WATER1. Energy from water can be used to generate electricity.2. Huge dams are built in high-altitude areas to

accumulate rain and river water.3. The gravitational potential energy changes to kinetic

energy when the water flows to the bottom to rotate the turbine in the hydroelectric power station.

4. The turbine then rotates a dynamo. The movement of the dynamo generates electricity.

5. To obtain this type of energy, dam construction involving a high cost is needed and it requires a large area.

6. The disadvantages of this source of energy are it upsets the balance of nature and destroys the natural habitats of many living organisms.


TIDAL WAVES1. Tides are caused by the gravitational force

of the Moon and the rotation of the Earth.2. Energy from the tidal waves can be used to

rotate a turbine and generate electricity.3. The disadvantages of producing this type of

energy are the difficulty to get a suitable place to build the station and its high cost.


GEOTHERMAL1. Geothermal energy is the heat energy

released from the centre of the Earth.2. High cost of construction is involved in order

to get this energy.3. The areas suitable for producing geothermal

energy are limited.

NON-RENEWABLE SOURCES OF ENERGY

FOSSIL FUELS1. Fossil fuels such as petroleum and natural

gas originate from animal and plants remains which have been buried in the crust of the Earth millions of years ago.

2. The use of this energy sources can cause several problems:

a) Health problemb) Production of acidic gases such as sulphur

dioxidec) Pollution of the environment

NON-RENEWABLE SOURCES OF ENERGY

Radioactive Substances1. Nuclear energy is produced by radioactive

substances.2. The most commonly used radioactive

substances are uranium and plutonium.3. The cost of constructing a nuclear reactor is

high and it difficult to obtain suitable elements.

6.2.2 THE NEED TO CONVERSE ENERGY

1. The development of a country depends on the availability of natural sources of energy.

2. Energy makes our standard of living higher.3. There are many benefits that we can obtain

from renewable and non-renewable sources of energy. The following shows some examples.

a) Petrol makes our vehicles move faster and effectively.

b) Communication devices make it easier for us to contact people abroad.

c) Solar energy is a good alternative for generating electrical energy, especially in tropical countries.

6.2.3 WAYS TO USE ENERGY EFFICIENTLY

1. A certain percentage of energy lost in the form of heat energy when changes of energy take place.

2. We have to use energy efficiently.3. We can invent equipments that can change the

heat energy released to useful mechanical energy.4. Electrical energy should be used more efficiently.5. We have to use alternative sources of energy

more widely.6. Solar, wind and wave energy can be used with the

help of more sophisticated and efficient equipments.

7. We can construct buildings that use more of solar energy.

6.3 THE IMPORTANCE OF CONSERVING ENERGY SOURCES

1. Natural sources of energy are very important to us in our daily lives.

2. Conserving the natural sources of energy is very important to:

a) Delay the depletion of non-renewable energy sources

b) Avoid wastage of energyc) Ensure that energy is widely used in the

fields that need itd) Avoid bad effects on humans and the

environment

6.3.2 THE USE AND MANAGEMENT OF SOURCES OF

ENERGYWe can use and manage energy efficiently by:1. Switching off electrical appliances when not in use.2. Recycling materials such as plastics, papers and

aluminium.3. Using wind to move turbines to produces electrical

and mechanical energy.4. Using public transports instead of driving cars

whenever possible.5. Using electrical appliances which use less energy.6. Ensuring that the machines are always in good

conditions.7. Creating solar-powered vehicles.8. Designing buildings that use solar energy.9. Using natural fertilizers and reducing the use of

pesticides.

Chapter 6

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