Transcript Slide 1

P1a Energy & Energy
Resources
Mr D Powell
2
Using Energy p242

K
S
U

Energy cannot be created or destroyed. It can only be transformed from one form to another
form.
When energy is transferred / transformed only part of it may be usefully transferred/
transformed.

Energy which is not transferred/transformed in a useful way is wasted.

To evaluate the effectiveness and cost effectiveness of methods used to reduce energy
consumption. i.e. Insulation

To describe the energy transfers/transformations and the main energy wastages that occur
with a range of devices to calculate the efficiency of a device

Both wasted energy and the energy which is usefully transferred/ transformed are eventually
transferred to their surroundings which become warmer.

The greater the percentage of the energy that is usefully transformed in a device, the more
efficient the device is.

Energy becomes increasingly spread out and becomes increasingly more difficult to use for
further energy transformations.
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2.1 Forms of energy
 (U) Both wasted energy and the energy which is
usefully transferred/ transformed are eventually
transferred to their surroundings which become
warmer.
 (K) Energy cannot be created or destroyed. It
can only be transformed from one form to
another form.
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What am I thinking of.....
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Make a table listing the items in the diagram and
link any energy changes you think apply;
Pendulum Kinetic -> GPE-> Kinetic
ELECTRIC
TORCH
PENDULUM
CANDLE
SPRING
HiFi
Torch
Electrical -> Heat -> Light
....
....
Gravitational Potential Energy
Chemical Potential Energy
Elastic Potential Energy
Heat (Thermal)
Light
Sound
Kinetic
Electrical
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Energy Changes...

A weight is raised using a winch driven by an electric motor. Use the
forms of energy listed below to complete the energy flow diagram.
1.
2.
3.
4.
5.
chemical energy
Chemical Energy
electrical energy
kinetic energy
gravitational potential energy
sound energy and thermal
energy due to friction
thermal energy due to resistance
of the wires
A.
Electrical Energy
B.
Kinetic Energy
D.
Gravitational PE
C.
Thermal wasted
E.
Sound
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More Energy Changes...

A falling weight can be used to light a lamp using a winch and a generator.
1.
2.
3.
4.
5.
electrical energy
kinetic energy
gravitational potential energy
light energy
sound and thermal energy due to
friction
6. thermal energy due to resistance of
the wires and lamp
chemical energy
GPE
A.
Kinetic
B.
Electrical
D.
Light
Thermal/ Sound
wasted
C.
Thermal in wires
wasted
E.
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Energy Transforms
 Use the pictures on this page to
inspire you to talk about the
energy changes on
rollercoaster's.
 Write an article (with diagrams)
designed for a magazine aimed at
GCSE / Year 9 pupils who need to
know about all the energy
changes involved in the
rollercoaster.
Possible Key Words....
Kinetic, GPE, Friction, Thermal, Useful,
Wasted, sound, velocity, acceleration...
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2.2 Conservation of energy

(K) Energy cannot be created or destroyed. It can only be
transformed from one form to another form.

(K) When energy is transferred / transformed only part of it
may be usefully transferred/ transformed.

(K) Energy which is not transferred/transformed in a useful
way is wasted.

(U) Energy becomes increasingly spread out and becomes
increasingly more difficult to use for further energy
transformations.
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Get thinking?
“tonight an in-depth look at what
each of us can do to help
conserve electricity”
Where has the energy gone?
What happens here....
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Energy Transformations...
Copy and complete the table below on the energy transformations....
Device
Initial energy
Useful energy
Waste energy
Portable radio
chemical
chemical
energy
sound
sound
energy
thermal
Food mixer
electrical
electrical
energy
kinetic
thermal
Hairdryer
electrical
kinetic/ heat
sound
Gas fire
chemical
thermal
Light
Fridge
electrical
thermal
thermal
Table lamp
electrical
light
heat
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Food Chains

A good example of
energy which is lost to
the surroundings is a
food chain.

Use this graphic and
your own ideas to
present this with
examples of real food
chains. Explain clearly
where the energy goes
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Food Chains



growth
heat
locked into
cells
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



growth
heat
kinetic
sound
excretion





growth
heat
kinetic
sound
excretion
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US Energy uses / wastage 2002
Talking point...
What can you say about energy use in the US in 2002?
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Summary Questions
1.
Energy can _________
transformed from one form into other forms.
2.
Energy can be ___________
transferred from one place to another place.
3.
Energy cannot be ________
created or __________.
destroyed
4.
_______
useful energy is energy in the place we want
Stored or _______
it and in the form we need it.
5.
_______
wasted energy is energy that is not useful.
6.
Useful energy and wasted energy both end up being
transferred to the ____________
surroundings which become warmer.
7.
spreads out, it gets more and more difficult to
As energy _______
use for further energy transfers.
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2.3 Useful energy / 2.4 Energy and efficiency
and efficiency issues

(S) To describe the energy transfers/transformations and the
main energy wastages that occur with a range of devices to
calculate the efficiency of a device.

(U) The greater the percentage of the energy that is usefully
transformed in a device, the more efficient the device is.

(S) To evaluate the effectiveness and cost effectiveness of
methods used to reduce energy consumption. i.e. Insulation
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Which uses the lowest energy...
Can you sort these into a rough order....
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Which uses the lowest energy...
Can you sort these into an order....
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How much energy do appliances use....
Make a note of some of these appliances and their energy uses. Write a short
sentence to explain why they might be Power hungry....
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Efficiency Calculations
Can you work out the missing numbers for this table...
Efficiency =
Useful Energy
Energy Supplied
Device
Energy supplied
(in joules)
Useful energy
(in joules)
Waste energy
(in joules)
Efficiency
Electric motor
500
150
350
0.3
Desk lamp
300
60
240
0.2
PC monitor
5000
500
4500
0.1
Microwave
oven
50 000
40,000
10,000
0.80
Torch lamp
50
20
30
0.40
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Sankey Diagrams
Sankey diagrams summarise all
the energy transfers taking
place in a process. The thicker
the line or arrow, the greater
the amount of energy involved.
The Sankey diagram for an
electric lamp below shows that
most of the electrical energy is
transferred as heat rather than
light.
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Efficiency?

How do the sankey diagrams
show which light bulb is more
efficient? Describe two
devices and diagrams which
explain this point.
Ordinary electric lamps contain a thin
metal filament that glows when
electricity passes through it. However,
most of the electrical energy is
transferred as heat energy instead of
light energy.
Modern energy-saving lamps work in
a different way. They transfer a
greater proportion of electrical
energy as light energy.
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Accurate Sankey Diagrams
Notice how this diagram is completed to scale. The vertical
part of the scale is 2 squares = 10J of energy. Try and draw
these 4 in a similar way on one sheet of graph paper.
Torch with
Chemical -> Light
5J & Heat 95J
Car with Chemical > Kinetic 25J &
Heat 75J
Bunsen Burner
with Chemical ->
Heat 85J, Light 10J,
Sound 5J
Hairdryer ->
Electrical -> Sound
5J, Heat 20J,
Kinetic 75J
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Sankey Diagrams

This diagram represents energy transfer by the drill
motor. The manufacturer claims the drill motor has
an efficiency of 0.35. The drill motor is supplied with
3000 J of electrical energy when the hole is drilled.
1.
What form of energy does A represent?
2.
What does B represent and what forms of energy
are included in it?
3.
What is the useful energy transferred by the drill
motor used for?
4.
What is the useful energy from the drill motor?
5.
What is the energy wasted by the drill?
1.
2.
3.
4.
5.
Electrical
wasted thermal / sound
Kinetic
0.35x 3000J = 1050J
(1-0.35) x 3000J = 1950J
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Preventing Energy Transfers...
 For each of the following
transfers on the following
slides
i.e. Loft insulation...
 Write a sentence for each
one to describe the
transfers and how they are
slowed down....
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Insulation
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We can insulate our homes to keep the energy in.

Different forms of insulation save us different
amounts of money as they save different amounts
of energy
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Floor Insulation
This is usually used when installing an under floor heating
system. This consists of;
 carpet, ceramic tile, etc)
 screed
 water pipe
 floor insulation
 concrete sub-floor
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Cavity Wall Insulation II
This insulation is in the form of polystyrene beads. This
allows the house to breathe more freely than with the
Glassroc
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Cavity Wall Insulation
This is a very
modern form of
cavity wall. The
Glassroc is made
from glass fibres
matted together
and prevents
convection
currents
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Draught Excluders
These brush like structures
prevent convection currents
around doors and are very
cheap to fit.
They also come in a rubber seal
form to go around windows
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Double Glazing
Two glass sheets of glass create
a sandwich of trapped air.
This prevents conduction and
convection currents.
Often one surface has a special
coating to absorb the suns infra
red rays.
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