Download useful energy x 100

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Energy is something that is
needed to make things
happen.
Energy can make things move
or change.
Energy is not a substance or
an object that you can touch
or hold.
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Riding
Using
Mowing
The
Lighting
wind
amakes
a the
a
Energy
Parachuting
Running
motorbike
computer
tocandle
blow
lawns
things
happen
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The Law of Energy
Conservation
Has three parts:
Part 1 = “Energy must come
from somewhere. It is never
created out of nothing”
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In fact, most energy can
be traced back to
nuclear reactions
inside the sun which
transforms stored
energy in matter to
heat and light energy.
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Part 2 = “Energy may change
form but the amount stays the
same”
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Part 3 = “Energy can never be
destroyed, only transformed”
Most energy ends up as heat
energy.
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The whole law = “Energy is
never created or destroyed,
and the total amount of
energy always remains the
same”.
A scientific law states what will
always happen.
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Forms of Energy
Light
- Travels at
300,000km/s
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Sound
- Made by
vibrating
objects
- travel at
330m/s
through air
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Heat
- Affects the
movement of
particles.
- The more
energy, the
faster they go
and the higher
the
temperature
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Gravitational
potential
- is found in
objects that
can fall
i.e. Bart
- The further the
object can fall
the more GPE
it has.
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Nuclear
potential
- Stored in the
nucleus of an
atom
- Can release
huge amounts
of heat, light
and radiation.
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Kinetic
- the energy of a
moving object
- The faster or
heavier an
object is the
more kinetic
energy it has.
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Electrical
- The flow of
energy as
charged
particles called
electrons
move along a
conductor.
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Magnetic
potential
- The energy of
some metal
objects in a
magnetic field.
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Elastic potential
- Found in
objects that
have been
stretched or
squashed and
are able to
regain their
original shape
when released
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Chemical
potential
- Energy stored
in the bonds
between
atoms
- i.e. food
and fuel
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Active Energy
are those types of energy that
can be seen to change from
one type to another, i.e. you
see two types of energy.
Examples include fireworks
and avalanches.
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Active Energy Types
Light
Sound
Kinetic
Heat
Electrical
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Potential Energy
is also called stored energy
because it has the potential to
do something.
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Potential Energy Types
Gravitational
Elastic
Nuclear
Chemical
Magnetic
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Energy Transfer
Energy can be passed from
one object to another.
The transfer of energy does not
change the type of energy.
For example, eating food
moves chemical energy from
the food to you.
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When a room is heated all
objects in that room warm up
(gain heat) to the same
temperature.
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Energy Transformations
occur when energy changes
from one type to another.
A microphone transforms
sound energy into electrical
energy.
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A washing machine transforms
electrical energy to kinetic,
sound, heat and light energy
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The light, sound and heat
energies from this projector
came from electrical energy in
the wiring
which came from the water
falling through a turbine at a
power station
which came from rain falling from
the sky
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which came from evaporation
caused by the heat of the sun
which came from nuclear
reactions in the sun’s atoms
….
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This can be summarised as:
Nuclear  Heat Gravitational
 Gravitational  Kinetic 
Electrical  Heat + light +
sound
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Chemical potential energy in battery
What are the energy
Electrical energy in wiring
transformations
in
this
 Kinetic energy of propellor
battery-powered
toy
car?
 Kinetic energy of car
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Measuring Energy
Energy is measured in joules
and is given the symbol J.
Heating 1mL of water by 1°C
requires 4.2 joules of heat
energy.
Lifting 1kg up by 1m requires
10J of energy.
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1kilojoule = 1000 joules
1kJ = 1000J
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Power
The amount of energy that is
transformed in a machine every
second is the power rating (also
called wattage).
Power is measured in watts, W.
One watt is exactly the same as
-1
one joule per second: 1W = 1Js
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Wasting Energy
Some of the energy in
a transformation is
unable to be used.
For example, the heat
produced by a TV
does not make the
light or sound any
better. It is wasted
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Energy = useful + wasted
input
energy energy
The useful energy is the type
that does what you want.
The waste energy is the type
that you cannot use.
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Energy Efficiency
Designers try to produce
appliances that make as little
waste energy and as much
useful energy as possible.
Energy = useful energy x 100
Efficiency
Energy input
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Food Energy
Our bodies require
energy to keep us
active and alive. This
energy comes from our
food and drink.
Our bodies are also
designed to store
energy in case we
cannot get food.
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This was very useful for our
ancestors when food was not
always available e.g. 10,000
years ago and earlier.
We have not lost this ability
and store the extra energy as
fat.
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Our bodies use energy
which needs to be
replaced. If we don’t get
enough energy we
become tired and sick.
But, if we get more
energy than our bodies
use we can become
obese (fat).
Some people are obese
because of medical
reasons unrelated to their
diet.
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Therefore we need to eat a
balanced diet, i.e. one that
contains all the needed
nutrients but also one that has
just enough energy to keep us
going but not too
much that we
become fat.
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Exercise uses energy that can
reduce the amount of stored
fat.
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Energy Sources
People require huge amounts
of energy to keep cities going.
The most common form used
is electrical energy.
This energy comes from a
range of different types of
power plants.
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Some power plants use nonrenewable sources of fuel.
These include power stations
that burn coal,
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oil or gas. One day we will run
out of these fossil fuels.
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Other power plants use renewable
sources of fuel. These include
hydro power stations (dams),
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wind turbines
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and solar
panels.
We will never
run out of
these energy
sources.
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