Transcript Document

Energy Transfer
Syllabus
Title Page
Lesson 01 Types of Energy
Lesson 02 Energy Efficiency
Lesson 03 Conduction and Convection
Lesson 04 Radiation and Insulation
Lesson 05 Insulating Homes
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Energy
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Energy Transfers
16/07/2015
Aim:
 To define energy
 To explain the purpose of a transducer and their role in
the conservation of energy
 To identify energy transfers
Starter:
in rough
 Write down words / phrases about energy
 Compare with your neighbour
 Compare with your table
 Agree a definition of energy and one of you write it
down (can be more than one sentence)
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Energy
Definition:
 Energy is required to do anything (work) (e.g. heat up).
 Energy is always conserved, it is never used up or destroyed it is
transferred into another form (e.g. chemical to heat and light).
 A transducer changes energy from one form to another (e.g. a
match).
Symbol: E
Unit: J (joules)
Analogy:
 Energy is like money.
 To do anything costs money.
 Money is not used up but changes hands when you pay for
something.
Handout
Demo Burning Ethanol
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Types of energy
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There are two groups of energy and nine types you need
to learn
In rough write down what types of energy you can think
of in 1 minute (think about the burning ethanol demo)
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Types of Energy
ACTIVE (KINETIC) ENERGY
STORED (POTENTIAL) ENERGY
Electrical energy
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Types of Energy
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_________ _______ (KE) are all types of movement energy.
_________ _______ (PE) are all types of stored energy.
Type
KE or PE?
Example Sources
KE
flame
Kinetic (movement)
Heat (thermal)
Light
Gravitational
Chemical
Sound
Electrical
Elastic
Nuclear
Kids Hate Learning GCSE Energy Names
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On your white board write down the type of energy
1.
Energy in a toffee
2.
Energy in a running girl
3.
Energy causing a light bulb to light
4.
Energy given off by a stationary boy
5.
Energy in music
6.
Energy in a spring shot
7.
Energy in a diver
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Energy Transfers
Watch the demo (flour fire breathing)
What energy transfers are occurring?
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Example Energy Transfers?
electrical
electrical
sound
kinetic
kinetic
light
electrical
chemical
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More Complicated Examples
There can be more than one step
gravitational potential
kinetic
electrical
Energy can be transferred into more than one type
electrical
heat
sound
light
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Energy Circus
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Around the lab are a selection of transducers.
For each one identify
 All the energy transfers (every stage)
 Underline useful transfers
 Bracket wasted transfers
 Write the name and transfers into your books
Example (try in your books in pencil)
1. Catapult Girl
Chemical
kinetic
(sound)
(heat)
elastic
kinetic
Elastic
gravitational
(heat)
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Identifying energy transfers
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Energy Transfers
recap
Aim:
 To define a energy
 To explain the purpose of a transducer and their role in
the conservation of energy
 To identify energy transfers
Plenary:
on whiteboards
 Write down the two most important things you have
learnt this lesson.
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Efficiency
16/07/2015
Aim:
 To create sankey diagrams
 To calculate efficiency
Starter:
 Watch the Movie (Roller Coaster)
 Identify the energy transfers
 How is energy wasted?
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Wasted sound energy
If you can hear a device that is not designed to make noise then energy is
wasted as sound.
Examples of devices that waste energy as sound include:
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Wasted Heat Energy
If a device gets warm and it is not designed to get warm then energy is
wasted as heat.
Examples of devices that waste energy as heat include:
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Which Type of Energy is Wasted?
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Wasted Energy
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Energy is normally wasted as heat and sound
Wasted energy dissipates (spreads out) into the
surroundings.
This dissipated energy is too spread out to do useful
work and so cannot be re-used.
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Sankey Diagram – A Candle
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Sankey Diagram – A Candle
Energy in: Every second the candle transfers 100 joules of chemical energy
Energy out: 20 joules into light energy and 80 joules into heat energy
“Input” energy
100 J
electrical
energy
“Output” energy
20 J light energy
80 J heat energy
So each block represents 10J
Only the width matters not the length
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Sankey Diagram – Running Man
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Sankey Diagram - Running Man
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Energy in: Every second the man transfers 2000 J of chemical energy
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Energy out: ? of useful kinetic, ? of useful sound, ? of wasted heat
2000 J
chemical
energy
kinetic
energy
sound energy
heat energy
So each block represents 200 J
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Questions
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•
1.
2.
3.
4.
Draw Sankey diagrams for the following on graph paper.
Highlight the useful energy.
Leave the right hand side of the graph paper empty.
Light Bulb
input: Electrical 200J
output: Light 30J, Heat ?J
Fire
input: Chemical 200J
output: Heat 150J, Light ?J and Sound 20J
Drill
input: Electrical 1000J
output: Kinetic 300J, Sound 200J, Heat ?J
Computer
input: Electrical ?J
output: Sound 50J, Light 100J, Heat 80J and Kinetic 20J
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Questions
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1.
2.
3.
4.
Make Sankey diagrams for the following on graph paper.
Highlight the useful energy.
Leave the right hand side of the graph paper empty.
Light Bulb
input: Electrical 200J
output: Light 30J, Heat 170J
Fire
input: Chemical 200J
output: Heat 150J, Light 30J and Sound 20J
Drill
input: Electrical 1000J
output: Kinetic 300J, Sound 200J, Heat 500J
Computer
input: Electrical 250J
output: Sound 50J, Light 100J, Heat 80J and Kinetic 20J
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Energy Efficiency
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•
Definition:
• The amount of energy transferred usefully.
• Can never exceed 1 or 100%.
Equation:
• Efficiency = useful energy out
total energy in
• It has no Units
• It can be a %
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Example
a)
A TV Supplies 50J of heat energy, 50J of sound energy,
and 100J of light energy.
What is the useful energy out?
b)
What is the total energy in?
c)
Calculate the efficiency of the TV?
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Whiteboard Questions
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Questions
a)
b)
c)
1.
2.
3.
4.
What is the useful energy out?
What is the input energy in?
Calculate is the efficiency?
Light Bulb
input: Electrical 200J
output: Light 30J, Heat 170J
Fire
input: Chemical 200J
output: Heat 150J, Light 30J and Sound 20J
Drill
input: Electrical 1000J
output: Kinetic 300J, Sound 200J, Heat 500J
Computer
input: Electrical 250J
output: Sound 50J, Light 100J, Heat 80J and Kinetic 20J
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1) Light Bulb
Electrical 200 J
(total in)
170J
Heat
(wasted)
30J
a) useful energy out = 30J
b) total energy in = 200J
c) Efficiency = useful
total
= 30
200
= 0.15 or 15%
Light
(useful)
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2) Fire
Heat
(useful)
150J
Chemical
(total in)
200 J
a) useful energy out = 150 + 30
= 180 J
b) total energy in = 200 J
c) Efficiency = useful
total
= 180
200
= 0.9 or 90%
30J
Light
(useful)
20J
sound
(wasted)
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3) Drill
300J
Electrical 1000 J
(total in)
a) useful energy out = 300J
b) total energy in = 1000J
c) Efficiency = useful
total
= 300
1000
= 0.3 or 30%
Kinetic
(useful)
200J Sound
(wasted)
500J
Heat
(wasted)
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4) Computer
Sound
(useful)
50J
Electrical 250 J
(total in)
a) useful energy out = 170J
b) total energy in = 250J
c) Efficiency = useful
total
= 170
250
= 0.68 or 68%
100J Light
(useful)
80J
20J
Heat
(wasted)
Kinetic
(useful)
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Multiple-choice quiz
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Anagrams
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Efficiency
recap
Aim:
 To create sankey diagrams
 To calculate efficiency
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