Download - science form 1 Chapter 6 sources of Energy
CHAPTER 6
SOURCES OF ENERGY
THE VARIOUS FORMS OF ENERGY
1. Energy is the ability to do work.
2. The SI unit for energy is Joule (J).
3. There are various forms of energy.
a) Potential Energy
• Energy stored in an object because of its condition
and position.
• Examples:
i. A rock on top of a hill
ii. The water in the dam
iii. Fruit on a tree
iv. A stretched spring or elastic band
v. A bent ruler
vi. A book on a shelf
b) Kinetic Energy
• Energy possessed by a moving object.
• Examples
i. Flying birds
ii. Running water
iii. Wind
iv. Moving car
v. Spinning fan
vi. Waves
• Energy stored in a hot object.
• Energy that can raise the temperature of an object.
• Examples
i. Burning object v. Boiling water
ii. Lighted match sticks vi. Hot iron
iii. Lighted electric bulbs
iv. The heat from the sun
c) Heat Energy
• Energy from an object that emits light
• Examples
i. Lightning
ii. Fire
iii. Lighted candle
iv. Fire flies
v. Torch
vi. Lighted lamps
d) Light Energy
• Energy that is stored in chemical
substances.
• Examples
i. Chemical substances like batteries,
hydrochloric acid and sodium hydroxide
ii. Foods
iii. Fuels
e) Chemical Energy
• Energy produced by flow of electrical
charges (electric current).
• Examples
i. Dynamos
ii. Lightning
iii. Power stations
iv. Batteries or dry cells
v. Solar cells
f) Electrical Energy
• Energy produced by a vibrating object.
• Examples
i. Beating a drum
ii. Ringing a bell
iii. Thunder
iv. Whistling birds
v. Singing a song
g) Sound Energy
• Also known as atomic energy.
• Energy stored in the nucleus of an
atom.
• Examples
i. Produced by fission and fusion of atoms
ii. Atomic bomb
iii. Nuclear reactor
h) Nuclear Energy
SOURCES OF ENERGY
a) Sun - Solar energy
b) Water - Hydroelectric energy
c) Fossil fuels - Heat energy
d) Biomass fuels - Biomass energy
e) Wind - Wind energy
f) Geothermal sources - Heat energy
g) Radioactive - Nuclear energy
substances
a) Sun
1. Sun is the primary source of energy on Earth.
2. Energy derived from the sun is called Solar
energy.
3. Heat and Light are two forms of solar energy.
4. Solar cells absorbs light energy from the sun
directly and change it into electrical energy.
5. Example: calculators, watches, satellites
6. Solar heater changes energy from the sun
to heat energy to heating up water and
cooking purposes.
1. Electricity generated using water is called
hydroelectricity.
2. Hydroelectricity is produced in power
stations by forcing the water from a dam
to flow and rotate turbines and dynamos.
b) Water
1. Fossil fuels are combustible materials which
means that they burn easily to release heat
and light energy.
2. Examples of fossil fuels:
a) Oil (petroleum and crude oil)
b) Natural gas
c) Coal
3. Fossil fuels provide heat energy to generate
electricity.
c) Fossil Fuels
1. Fuels such as firewood, paddy husks, dry
leaves, animal faeces and household
waste which are biological materials are
known as biomass fuels.
2. These fuels produce biomass energy.
3. Biomass energy is used for working
machines and moving vehicles.
d) Biomass Fuels
1. Wind is moving air which contains kinetic
energy.
2. Wind mills have been used for pumping water,
grinding grains and drive machines.
3. A wind turbine is used to generate electricity
using wind energy.
e) Wind
1. The heat energy from the very hot interior of
the Earth is called geothermal energy.
2. Most of the geothermal areas are near
volcanoes, hot springs and geysers.
3. Geothermal energy produces steam which is
used to drive generators to produce electricity.
f) Geothermal Sources
1. Radioactive substances like Uranium and
Plutonium can be used produce nuclear
energy.
2. Nuclear reactions generate lots of heat
energy that can be used to produce steam
that drives generators to produce electricity.
g) Radioactive Substances
3. This electricity is used for:
i. War ships
ii. Submarines
iii.Satellites
iv.Meteorological stations
v. Light houses
ENERGY CHANGES
1. The principle of conservation of energy
states that energy cannot be created or
destroyed but can be changed from one
form to another.
2. The total amount of energy in the world is
fixed. Total energy before change = total energy after change
3. When a marble rolls down an inclined slope,
potential energy changes into kinetic energy.
*copy the diagram form text book
i. Point A – highest point on the slope
ii. Point C – lowest point on the slope
iii. At point A, the marble has the maximum potential
energy.
iv. When the marble rolls down to point B, it has both
potential energy and kinetic energy.
Potential Energy Kinetic Energy
v. At point C, all of the potential energy has
changed into kinetic energy.
vi. The marble moves faster at point C.
vii.At point C, the marble has maximum
kinetic energy.
4. Example of energy change:
RENEWABLE AND NON - RENEWABLE ENERGY
1. The sources of energy in this world can
be classified into two groups:
a. Renewable Energy Sources
b. Non − renewable Energy Sources
2. Renewable energy sources exists
continuously and can be replenished or
renewed when they have been used.
3. Examples of renewable energy
sources:
a. Sun – solar energy
b. Flowing water – hydroelectric energy
c. Plants – biomass energy
d. Wave – wave energy
e. Wind – wind energy
f. Geothermal resources – geothermal
energy
4. Non – renewable energy sources are that
cannot be replenished or renewed and will
eventually be used up and exhausted.
5. Examples of non – renewable energy
sources:
a) Fossil fuels – petroleum, crude oil, natural
gas and coal
b) Radioactive substances
WAYS TO USE ENERGY EFFICIENTLY 1. Use energy saving electrical appliances
2. Recycle used things such as old
newspapers and plastics
3. Share cars (carpool) or use public
transport such as commuter or LRT
4. Do not leave electrical appliances
switched on when they are not in use
5. Find alternative sources of energy such
as solar energy and wind energy
THE IMPORTANCE OF CONSERVING ENERGY SOURCES
1. Energy sources must be conserved
because half of the energy sources will
be depleted in a 100 – year cycle.
2. Conserving energy sources are
important because:
a. It will reduce the wastage of energy
b. It will enable the non – renewable
energy sources to last longer
c. It will ensure the energy sources last
for the future generations
EXERCISE
1. Circle the names of the objects below
which shows examples of Potential
Energy.Stretched elastic band
Radio
Compressed spring
Solar cell
Wound toy car
2. Draw lines to match the energy converter to its energy change.
Electrical fan ● ● Kinetic energy → Electrical energy
Dynamo ● ● Electrical energy → Kinetic energy
Plants ● ● Light energy → Chemical energy
2. f
3. The diagram below shows four sources of
energy. Name each of the sources of
energy.
P Q R
S
a. P:
b. Q:
c. R:
d. S:
Wind
Fossil FuelNuclear SubstancesWater