Energy
Energy is the power behind our world. Although you
can’t see it, you can’t do much without it. Whenever
things move, light up, change shape, get hotter or
colder, or make noises, energy is involved.
STORED ENERGY
You can do two things with energy: store it or use it.
It takes lots of energy to ride a bike up a hill, but
that energy doesn’t disappear. It’s stored by your body
and by your bike in a form called potential energy.
You use this stored energy when you race back
down without pedaling. The potential
energy you stored is then converted
into kinetic energy
(movement energy).Freewheeling
turns potential
energy into
kinetic energy.SCIENCE
Kinetic
The energy moving
things have. Race
cars have lots of
kinetic energy.Light
A kind of kinetic
energy carried by
invisible waves of
electricity and
magnetism.Electromagnetic
Electromagnetic
energy is also
carried by radio
waves, X-rays, and
microwaves.Heat
Hot things have
energy because their
atoms or molecules
move more quickly.Electrical
Electricity is a
convenient form of
energy that can be
carried along wires.Nuclear
Atoms can release
energy from their
nucleus (central
core).Gravitational
Falling things, like
this waterfall, release
potential energy
stored using gravity.Heat sensitive photograph There’s a fixed amount of
energy in our universe. We can’t make any more or use
any up. All we can do is change energy to other forms.
When a car brakes, its kinetic energy doesn’t vanish. It
changes to heat in the brakes and wheels (glowing in this
heat-sensitive photograph).RENEWABLE
ENERGY
Earth has limited amounts of
fossil fuels, such as oil, coal, and
gas. Once we’ve used them, there will
be no more. There are unlimited
amounts of renewable energy. This
includes energy from the Sun, the
wind, and the oceans. We can
go on using renewable
energy forever.TYPES OF ENERGY
Energy exists in many different forms.
Almost everything we do involves
changing energy from one form into
another. When we’re “using” energy, we’re
actually converting it into another form.CHANGING ENERGY
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(c) 2012 Dorling Kindersley. All Rights Reserved.(c) 2012 Dorling Kindersley. All Rights Reserved.