Download Science Year 7 Learn Sheet DC4 – Energy

Energy from the sun.
Energy transfers and stores.
Energy from food.
Most of the energy
resources we use store
energy that originally came
from the Sun.
Only geothermal power,
nuclear power and tidal
power do not depend on
energy from the Sun.
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Humans and other animals need energy to live.
The energy resource for our bodies is the energy stored in
food.
We need to choose our food so that we get the right amount of
energy.
The unit for measuring energy is the joule (J).
There is a lot of energy stored in food, so we usually measure
the energy in food using kilojoules (kJ). 1 kJ = 1000 J
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Renewable energy
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include solar, wind, tidal,
wave, biofuels, geothermal
and hydroelectricity
do not produce harmful
gases or contribute to global
warming
are often more expensive
than using fossil fuels
will not run out
are not always available.
Hydroelectricity,
geothermal energy and
biofuels are available at any
time.
Tidal power is not available
all the time, but we can
predict when it will be
available.
Energy from solar, wind and
waves is only available some
of the time.
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Key words:
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Energy: Something that is needed to make things happen or change.
Joule (J): The unit for measuring energy.
Kilojoule (kJ): There are 1000 joules in 1 kilojoule.
Chemical energy: A name used to describe energy when it is stored in chemicals. Food, fuel and
batteries all store chemical energy.
Elastic potential energy: A name used to describe energy when it is stored in stretched or
squashed things that can change back to their original shapes. Another name for strain energy.
Gravitational potential energy: A name used to describe energy when it is stored in objects in
high places that can fall down.
Thermal energy: A name used to describe energy when it is stored in hot objects. The hotter
something is the more thermal energy it has
Fossil fuel: Coal, oil and natural gas – all fuels that were formed from the remains of dead plants
and animals.
Fossil Fuels
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are made from plants and animals that were trapped in mud and rocks
millions of years ago
include coal, oil and natural gas
are non-renewable (they take millions of years to form, and so our
supplies will run out)
produce gases that cause pollution and global warming when burnt
are relatively cheap to obtain
originally got their energy from the Sun. The plants that became coal, oil
and natural gas got their energy from the Sun, and the animals that
became oil and natural gas got their energy from plants, which got their
energy from the Sun.
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Energy can be transferred by: ●
heating ● light ● sound ●
electricity ● forces.
the chemicals in food, fuels and
batteries chemical energy
moving objects kinetic energy
hot objects thermal energy
objects that are stretched,
squashed or twisted strain energy
or elastic potential energy
objects moved to high places
gravitational potential energy
inside the particles that
everything is made up from nuclear
energy or atomic energy
Energy is not used up. It can be
transferred and stored in
different ways, but it cannot be
created or destroyed. This is
called the law of conservation of
energy
Fuels.
• Fuels store energy, and this energy
is transferred when the fuels
burn.
• Burning fuels are used to heat
things.
• Nuclear fuel is also non-renewable.
Nuclear power stations produce
dangerous waste materials.
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Electricity is not a fuel. It has to
be generated using other energy
resources.
Revision Questions
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Name all the types of energy you have studied in this unit. For each
one, state one place it could be observed.
What does ‘conservation of energy’ mean? What is the rule for
conservation of energy?
Draw an energy transfer diagram for a toaster. (Ext: label the
useful and wasted energy). Use this diagram to explain what
efficiency is.
Name 2 renewable energy sources. Explain the advantages of using
renewable energy. Explain what renewable means.
Name 2 non-renewable energy sources. Explain what non-renewable
means.
What are fossil fuels? Give the definition and some examples.
Why are fossil fuels bad for the environment? Explain at least 3
reasons.
Explain how geothermal power stations work – include a diagram with
your answer.
Explain how hydroelectric power stations work – include a diagram
with your answer.
Revision Questions
1. Name all the types of energy you have studied in this
unit.
2. What does ‘conservation of energy’ mean?
3. Draw an energy transfer diagram for a toaster. (Ext:
label the useful and wasted energy).
4. Name 2 renewable energy sources. Explain the
advantages of using renewable energy.
5. Name 2 non-renewable energy sources.
6. What are fossil fuels?
7. Why are fossil fuels bad for the environment?
8. Explain how geothermal power stations work – include a
diagram with your answer.
9. Explain how hydroelectric power stations work –
include a diagram with your answer.