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KS4 Physics
Types of Energy
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Contents
Types of Energy
Different types of energy
Nuclear energy
Gravitational potential energy
Kinetic energy
Summary activities
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Rita’s bedroom
Rita is not very energetic in the morning.
What types of energy can you see in her bedroom?
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Different types of energy
Energy cannot be seen or
observed directly and can be
thought of as the ability to do
work.
Energy exists as different types
and can be transferred, or
changed, from one form to
another.
The amount of energy an object
has is measured in joules (J).
There are nine different types of
energy that you need to be
aware of:
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1. ______________
light
sound
2. ______________
kinetic
3. ______________
nuclear
4. ______________
electrical
5. ______________
chemical
6. ______________
elastic
7. ______________
gravitational
8. ______________
thermal
9. ______________
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Light energy
Light is a form of electromagnetic
radiation. This is energy carried
by vibrating electric and magnetic
forces in transverse waves.
Light travels in straight lines
and has the properties of waves.
The Sun is a light source, as is
a filament lamp or a firefly.
How do we see objects?
by reflected light
Which colour of light has the
most energy: red or violet?
violet
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Sound energy
Sound energy needs a
medium through which to
travel.
Sound energy is transmitted
by vibrations of the particles
in the medium through which
it is travelling .
Sound travels in longitudinal
waves.
The louder the sound, the
more energy it transmits.
The quieter the sound, the
less energy it transmits.
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Thermal energy
All objects have thermal energy. It is the energy a substance
has due to the kinetic energy (movement) of its particles.
The more thermal energy a material has, the hotter it is.
In which state of matter (solid, liquid or gas), do water
molecules have the most thermal energy and why?
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Thermal energy
Ice (frozen water)
has the least
thermal energy.
Its molecules
have little kinetic
energy and so are
unable to move
past each other.
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Liquid water has
more thermal
energy.
Its molecules
have more kinetic
energy. They can
move past each
other but are still
held together.
Water vapour has
the most thermal
energy.
Its molecules
have lots of kinetic
energy and are
moving so fast
they are no longer
held together.
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Electrical energy
Electrical energy is carried
by wires and is the energy
that electrons have as
they flow around a circuit.
Electricity is useful
because it is a convenient
way of transporting energy
to a particular location or
device.
Electrical energy can
be used to do work in
a wide range of
different devices.
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Elastic energy
If a material like this sponge
is squashed (compressed),
when the material is released
it has the potential to return
to its original shape.
The energy stored in a
compressed material is
called elastic energy.
The same is true for
materials that are stretched
and have the potential to
return to their original shape.
They also store elastic
energy.
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Chemical energy
Chemical energy is a type
of stored energy that is
released by chemical
reactions.
Fuels, food and batteries all
contain chemical energy.
When a fuel burns, energy
is released by a chemical
reaction with oxygen.
Respiration is the process
used by the body to release
the chemical energy stored
in digested food.
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Contents
Types of Energy
Different types of energy
Nuclear energy
Gravitational potential energy
Kinetic energy
Summary activities
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Nuclear fission
The particles in the nucleus
of an atom are held together
by strong forces.
Some atoms, such as
uranium, have a very large
unstable nucleus, which can
split into two smaller nuclei.
This splitting is called fission
and releases huge amounts
of nuclear energy.
The release of nuclear
energy is exploited in
nuclear power stations and
some atomic bombs.
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Nuclear fission
A uranium nucleus is split by bombarding it with neutrons.
This fission forms two new elements and two neutrons.
The new neutrons can cause other nuclei to split, which
releases even more neutrons. This is a chain reaction.
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Nuclear fusion
Atomic nuclei can join together, which also releases huge
amounts of energy. This joining together is known as fusion.
Nuclear fusion is the process that releases energy inside
stars such as the Sun.
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Nuclear energy summary
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Contents
Types of Energy
Different types of energy
Nuclear energy
Gravitational potential energy
Kinetic energy
Summary activities
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Gravitational potential energy
Any object in a gravitational field has gravitational potential
energy due to its position in that field.
The Moon has gravitational
potential energy due to the
gravitational field of the Earth.
The Earth has gravitational
potential energy due to the
gravitational field of the Sun.
The gravitational potential energy depends on the
distance between the two objects.
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Gravitational potential energy
The gravitational potential
energy of an object on Earth
depends on its weight and
its height above the Earth’s
surface.
When a bungee jumper
starts to fall they start to
lose gravitational potential
energy.
As the elastic cord pulls the
bungee jumper back up,
they gain gravitational
potential energy.
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Calculating gravitational potential energy
The gravitational potential energy (GPE) of an object
depends on its weight and its height.
The equation for calculating GPE is:
GPE = weight x height
What are the units of GPE, weight and height?
 GPE is measured in joules (J).
 Weight is measured in newtons (N).
 Height is measured in metres (m).
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Calculating gravitational potential energy
The weight of an object is its mass multiplied by the strength
of the gravitational field acting on the object.
This can be substituted into the GPE equation to give:
GPE = weight x height
gravitational
GPE = mass x field strength x height
What are the units involved?
 GPE is measured in joules (J).
 Mass is measured in kilograms (kg).
 Gravitational field strength is measured in newtons per
kilogram (Nkg-1).
 Height is measured in metres (m).
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Gravitational potential energy problem
A seagull with a weight of
30 N flies at a height of
10 m above the ground.
How much gravitational
potential energy does the
seagull have?
GPE of seagull = weight x height
= 30 N x 10 m
= 300 J
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Calculating gravitational potential energy
When an object falls or is raised, it is useful to calculate the
change in gravitational potential energy (GPE).
To do this, the change in height is used in the GPE equation:
GPE = weight x height
change in GPE = weight x change in height
What are the units involved?
 Change in GPE is measured in joules (J).
 Weight is measured in newtons (N).
 Change in height is measured in metres (m).
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Gravitational potential energy problem
A parachutist of weight 600 N
jumps from a plane, which is
2000 m above the ground.
How much gravitational
potential energy will the
parachutist have lost when
she reaches the ground?
GPE = weight x height
change in GPE = weight x change in height
= 600 N x 2000 m
= 1 200 000 J
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Gravitational potential energy problems
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Contents
Types of Energy
Different types of energy
Nuclear energy
Gravitational potential energy
Kinetic energy
Summary activities
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Kinetic energy
Kinetic energy is the energy an object has because
it is moving.
 The greater the mass of a moving object,
the greater its kinetic energy.
If the mass is doubled, the kinetic energy is doubled.
 The greater the velocity of a moving object,
the greater its kinetic energy.
If the velocity is doubled, the kinetic energy is quadrupled!
So, if the velocity of a car is slightly above the speed limit,
its kinetic energy is much greater than it would be at the
speed limit. This means it is more difficult to stop the car
and there is more chance of an accident.
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Calculating kinetic energy
The kinetic energy (KE) of an object depends on its mass
and its velocity.
The equation for calculating kinetic energy is:
kinetic energy = ½ x mass x velocity2
KE = ½mv2
What are the units of kinetic energy, mass and velocity?
 Kinetic energy is measured in joules (J).
 Mass is measured in kilograms (kg).
 Velocity is measured in metres per second (ms-1).
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Kinetic energy problem
A car has a mass of 1500 kg
and is travelling at a velocity
of 10 ms-1.
What is the kinetic energy of
the car?
kinetic energy = ½ x mass x velocity2
= ½ x 1500 kg x (10 ms-1)2
= 75 000 J
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Rearranging the kinetic energy equation
Sometimes it is necessary to rearrange the kinetic energy
equation in order to calculate the mass or the velocity of
a moving object.
KE = ½mv2
What are the rearranged versions of this equation for
calculating mass and velocity?
mass =
2KE
v2
velocity =

2KE
m
TIP: If you do not think you can rearrange the KE formula
during an exam, learn the rearranged formulae instead.
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Kinetic energy problem
A train has a mass of 100 000 kg.
If its kinetic energy is 3 MJ,
what velocity is it travelling at?
3 MJ = 3 000 000 J

=

velocity =
2KE
m
2 x 3 000 000
100 000
=  60
= 7.75 ms-1
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Kinetic energy problems activity
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Contents
Types of Energy
Different types of energy
Nuclear energy
Gravitational potential energy
Kinetic energy
Summary activities
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Glossary
 chemical energy – The energy stored in chemicals and
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which is released when they react.
elastic energy – The energy stored in a material because
it is being stretched or compressed.
gravitational potential energy – The energy an object
has because of its position in a gravitational field.
kinetic energy – The energy an object has because it is
moving.
nuclear energy – The energy stored in an atom’s nucleus.
nuclear fission – The splitting of a large nucleus into two
nuclei, which releases very large amounts of energy.
nuclear fusion – The joining together of two atomic nuclei,
which releases very large amounts of energy.
thermal energy – The energy of a substance due to the
movement of its particles.
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Anagrams
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Multiple-choice quiz
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