energy
● Energy is the ability to do work.
● Both living and non-living systems need to function.
FORMS OF ENERGY
Potential Kinetic Light Heat Electrical Sound
energy energy energy energy energy energy
Potential energy
Potential energy is the energy that is stored in a body
as a result of its position/condition.
There are 4 different
forms of potential
energy:
(a) gravitational
potential energy
(b) elastic potential
energy
(c) chemical energy
(d) nuclear energy
Gravitational Potential Energy
Gravitational potential energy is the energy that is
stored in a body as a result of its elevated position.
When a wreck ball is raised
above the ground, it stores
energy due to its elevated
(raised) position in the air.
(a) Same Height, Different Mass
The greater the mass of an object and its height from the
ground, the greater the gravitational potential energy
Higher gravitational Lower gravitational
potential energy potential energy
If both of the trees
are at the same
height, a coconut has
higher gravitational
potential energy
compared to an apple
because the mass is
greater.
(b) Same Mass, Different Height
Higher gravitational
potential energy An apple of the same
mass falling from a high-
rise building has higher
gravitational potential
energy compared to the
lower buildings.
Lower gravitational
potential energy
elastic Potential Energy
Elastic potential energy is the energy that is stored in a
object (an elastic object) when it is pushed or pulled.
Spring is an example
of elastic object. It can
be pulled down when
a weight is attached to
it and spring back to
Spring its original shape when
the weight is removed.
When an elastic object is pushed or pulled, it stores
energy which can be released to do work.
❶ When the bow is stretched, the string of the
bow stores some elastic potential energy.
❷ Once he releases
the string, the
energy stored in the
string will push the
arrow forward and
work is done.
Oxygen Sugar Carbon Water Energy
dioxide
Energy is
released when
our food is
broken down
into smaller
molecules.
nuclear Energy
Nuclear energy is the energy that is stored in the nucleus
of an atom and is released during nuclear reactions.
A lot of nuclear energy is needed to
Nucleus
hold the protons and neutrons together
in the nucleus of an atom. Thus, large
amount of energy is released during
nuclear reactions.
Solid Liquid Gas
kinetic energy
Kinetic energy is an energy that a body possesses due to its
motion. All the things that are moving possess kinetic energy.
The Effect of Mass and Speed
High speed, high kinetic energy
Kinetic energy depends on speed. The faster an object
moves, the greater the kinetic energy. That’s why high-
speed crashes are more severe and more likely to be fatal.
Truck Car
Mass: 10,000 kg Mass: 500 kg
Speed: 100 km/h Speed: 100 km/h
High mass, high kinetic energy
If two objects are traveling at the same speed, the
object with a larger mass will have larger kinetic energy.
Thus, a truck has more kinetic energy than a car
light energy
Light energy is a form of energy which enables us to see.
The Sun is our main
source of light.
Plants trap energy
in the sunlight to
make food in a
process called
photosynthesis.
Solar cells collects light
energy from the Sun and
convert it into electrical
energy to operate the
calculator.
Solar
cells
heat energy
Heat energy is a form of energy which flows from a region
of higher temperature to a region of lower temperature.
• When an object gains heat, its
temperature increases.
• When an object loses heat, its
temperature falls
ENVIRONMENT
25 oC
Heat flows from
the container
CONTAINER (hotter) to the
HEAT oC HEAT
70 surrounding
(cooler)
ENVIRONMENT
25 oC
Heat flows from
surrounding
CONTAINER (hotter) into
HEAT oC HEAT
10 container
(cooler)
electrical energy
Electrical energy is a form of energy made available by
the flow of electrical charges such as electrons and ions.
Many modern devices, machines and lightings
run on electrical energy
Power
point
Electrical cells
Power point
Electrical cells and power points are main sources
of electrical energy. The electrical energy from the
power point comes from power stations.
Types of energy
Renewable Energy Non-renewable Energy
● Sources that can be ● Sources that cannot be
replenished in short replenished in short
period of time period of time.
● Example: ● Example:
– solar – petroleum and gas
– wind – nuclear
– geothermal
– hydroelectric
– biomass
Solar energy
● A form of energy that
uses light from the
Sun and convert it into
electrical energy in
order to operate the
electrical appliances.
● The Sun is the main
source of solar energy.
Advantages of Solar Disadvantages of Solar
Energy Energy
• free energy from the • electricity to be stored in
Sun batteries
• clean because no • not produced at night
pollutants produced • only for countries that
receive a lot of sunlight
wind energy
● A form of energy which uses
wind to generate electricity by
kinetic energy produced when
the blades are turned.
● The main source of wind
energy is the wind.
Energy Conversion
Kinetic energy
(the strong wind
Blade
turns the blades
the turbine)
Electrical energy
(converted by
the generator)
Mechanisms of Wind
Energy Production
Blade Wind blows and
turns the turbines
Turbine
Generator The moving blades then
moves the generator
The generator converts
the kinetic energy to
electrical energy
Advantages of Wind Disadvantages of Wind
Energy Energy
• free energy from the • wind does not blow all
wind the time
• clean because no • loud noise made by the
pollutants produced spinning turbines
• renewable resource
– it cannot be used up
Geothermal energy
● A form of energy which
uses the heat from the
Earth to create steam
which will eventually
turn the turbine and
generator to create
electrical energy.
● The main source of
geothermal energy are
the hot spring or hot
rock.
Energy Conversion
Turbine
Hot water
out
Cold water in
Generator
Heat Kinetic energy Electrical energy
(from the center (hot vapor spins (conversion by
of the Earth) the turbine) generator)
Mechanisms
Turbine
Hot water
out
Cold water in
Generator
Cold waters are pumped Hot rocks or magma
under hot rocks or heats up the water are
surface of the Earth pumped up again
Hot water Turbine
out
Cold water in
Generator
The steams turn The generator converts
turbines and the kinetic energy to
generators too electrical energy
Advantages of Disadvantages of
Geothermal Energy Geothermal Energy
• free energy from the • only certain parts of the
Earth’s center Earth where hot rocks
• clean because no can be found
pollutants produced
• renewable resource
– it cannot be used up
hydroelectric energy
● A form of energy that
uses the gravitational
potential energy of
water to spin the
turbine and generator
to produce electricity.
● It is built at the base of
a reservoir.
● Water is the main
source of this energy.
Energy Conversion
Gravitational potential
energy
Electrical energy
Kinetic energy
Gravitational Kinetic Electrical
potential energy energy energy
(water coming (water spins (conversion by
down the pipe) the turbines) generator)
Advantages of Disadvantages of
Hydroelectric Energy Hydroelectric Energy
• cheap because no fuel • reservoir take up large
needed to run the plant spaces and it will
• clean because no destroy the countryside
pollutants produced • can only built in hilly
• renewable resource areas with large water
– water can be replaced source
when it rains
Biomass energy
● A form of energy that
uses animals and
plants’ wastes to
produce methane
(natural gas) which
can be use to run
vehicles or to burn in
order to produce
electricity.
● The main source of
this energy is animal
and plant’s wastes.
(a) Dead animals & plants
When animals and plants rot in the absences of
air, a mixture of biogas (methane) will be
produced. Methane is then burn to produced
heat and eventually to generate electricity.
(b) Alcohol
Ethanol, a type of
alcohol is, corn or other
sugar based plants
through a process called
fermentation.
Ethanol is used as a fuel
to run motor vehicles or
burn it to produce heat
and electricity produced
when sugarcane
(c) Wastes
Household waste such
as food waste can be
burnt to produce
energy. It can also be
buried and allowed
the production of
methane, that will
eventually use as a
fuel to generate heat
or electricity
Energy Conversion
Chemical Heat Kinetic energy Electrical energy
energy energy (steam turns (conversion by
(wastes) (the steam) turbine) generator)
Mechanisms
The wastes The steam turns Generator converts kinetic
are burned the turbine energy into electrical energy
Advantage of Biomass Disadvantage of Biomass
• cheap because wastes • the gas produced from
are readily available combustion of methane
will cause global warming
Fossil fulled energy
CRUDE OIL
NATURAL GAS
Fossil fuels are rich in
carbon and hydrogen. They
burn in the air to produce
heat and light energy.
COAL
Fossil fuels are widely
used as sources of
energy in transport,
homes and industries.
Many vehicles run on
petrol and diesel,
which is obtained
from crude oil.
Formation of Coal
SWAMP WATER
300 million years ago 100 million years ago
Before the dinosaurs, Over millions of years, Heat and pressure
many giant plants the plants were buried turned the dead
died in swamps under water and dirt. plants into coal
Formation of Crude Oil
OCEAN OCEAN
300 million years ago 100 million years ago
Tiny sea plants and Over millions of years, Today we drill down
animals died and were the remains were buried through layers of sand,
buried on the ocean deeper and deeper. The silt and rock to reach
floor. Over time they enormous heat and the rock formations
were covered by pressure turned them that contain oil and gas
layers of silt and sand. into oil and gas deposits
Energy Conversion
Hot steam
Turbine
Generator
Burning coal Cool water
Chemical Heat Kinetic energy Electrical energy
energy energy (steam turns (conversion by
(coal) (the steam) turbine) generator)
Mechanisms
Hot steam
Turbine
Generator
Burning coal Cool water
The burning The steam The turbine turns
coal heats up turns the the generator to
the cold water turbine produce electricity
Advantages of Fossil Disadvantages of Fossil
Fuels Energy Fuels Energy
• can produce large • nonrenewable – it will
amount of energy finish after using it up.
• power station can be • production of harmful
build anywhere pollutants, examples
carbon dioxide, carbon
monoxide, nitrogen
oxide and etc
• the mining of fossil fuels
causes damage to the
environment
Mexican Gulf Oil Spill
Mexican Gulf oil ring has spilled between 17 and 39 million
gallons, making it the worst spill in American history.
The National Wildlife Federation reports that already
more than 150 threatened or endangered sea
turtles are dead. And 316 sea birds, mostly brown
pelicans and northern gannets, have been found dead.
Honkeiko Colliery, China
April 26, 1942, the worst mining disaster of all time, 1,549
miners died in a mine operated in Japanese occupied
Manchuria. China has a horrible history of mine safety.
Nuclear energy
Nuclear energy is made when uranium is split with accelerated
neutron and a huge amount of heat energy is produced.
Accelerated neutrons
Lighter
element
Neutron
+ HEAT
Lighter
element
Uranium 235 Neutron
Chernobyl Disaster
It occurred on 26 April
1986 and it is considered
the worst nuclear
power plant accident in
history.
It is estimated that 56
people died from the
direct explosion and a
total of 4,000 deaths due
to increased cancer risk.
Energy Conversion
Steam
Turbine
Nuclear
fission Generator
Nuclear energy Heat energy Kinetic energy Electrical energy
(energy in (from nuclear (steam turns (conversion by
uranium) fission) turbine) generator)
Mechanisms
Steam
Turbine
Nuclear Generator
fission
Nuclear fission As a result, The heat turns Generator
reactor splits large the water into converts
the nuclei of amount of steam which kinetic energy
uranium or heat is eventually turns to electrical
plutonium produced the turbines energy
Advantages of Nuclear Disadvantages of Nuclear
Energy Energy
• clean because no • nonrenewable – it will
pollutants produced finish after using it up.
• uranium used in nuclear • produces radioactive
reactors is inexpensive waste, which needs to
compared to the be carefully handled and
amount of electricity it stored.
can produce
Conversion of energy
Laws of conversion of energy
“ Energy cannot be created and destroyed only change from
one type to another ”
Chemical energy Light energy Heat energy
(fuel or coal) (fire) (hot)