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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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