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Назва What is energy (реферат)
РозділІноземна мова, реферати англійською, німецькою
ФорматWord Doc
Тип документуРеферат
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   What is energy.

   Everything in the universe is either energy or matter. For us humans,
energy is the means for doing work. Picking up a book, watching TV or
launching a Space Shuttle all needs energy. Without it there would be no
life, for all life uses energy. 

   Energy, so far as we are concerned, comes from only two sources: the
Sun and the decay of radioactive elements inside the Earth. The Sun
radiates its warmth out to all the planets, but ours happens to be about
the right distance away to be able to support Life. In fact, Life seems
to control the temperature of the planet like a thermostat. 

   But what about oil, gas or coal, which also come from inside the
Earth? They were formed because of the energy from ancient sunshine from
millions of years ago driving life on Earth. These have formed 'fossil
fuels' or 'non-renewable' energy sources. 

   Energy is the power that we use to do things, whether it is thinking
about building a ship or actually building it. Building it needs large
amounts of energy to power blast furnaces to make the steel, mills to
roll it and electricity to weld it to form the ship's structure. That
ship, when built, has engines, which push it through the water. Most
energy is not available to us in a usable form. We have to convert it
into another form to make it work for us. 

   Here are two examples: 

	A fast-flowing river is full of energy we can't use. If you dam it and
install turbines, you get electricity. 

	Coal is just black rock with one odd property ... it burns. If you burn
it, you can warm your home, cook food or raise steam in a boiler - to
make electricity. 

   Life needs energy. Life's energy is self-perpetuating only so long as
there is sunshine. Plants can convert it and store it for their next
generation (as in potato tubers, groundnuts, rice or peas). Animals eat
the plants or each other, die and decompose, freeing nutrients for
plants again. It is a sustainable cycle. For hundreds of thousands of
years, humans have merely been a part of this cycle. Then we got clever
and discovered that we could use energy other than from our own muscles
to do work for us. 

   First we discovered that wind could drive our ships and water could
power our mills. Later, we found that coal could make heat and steam for
machinery. Then came oil and gas and nuclear power, all needed in
increasingly large amounts to fuel our endless appetite for being
comfortable and doing things with as little effort as possible. So we
heat our homes, schools and workplaces in the winter. In the richer
countries, most people have a car (or several) so that they can travel
about. Transport guzzles huge amounts of energy - all so that we can
have goods and services when we want them.

Kinds of energy resources.

Almost all of the energy we use comes from non-renewable sources.

All non-renewable energy sources create pollution, in part due to their
extraction from the crust of our planet but mainly from their burning.
Only two types exist: the fossil fuels (coal, oil and natural gas) and
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