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ENERGY
The term energy comes from energeia, the Greek word for "work." Energy
is defined as the capacity to do work.
Energy cannot be created or destroyed, but it can change form. Heat, light, and
electricity are forms of energy. Other forms include mechanical, chemical, and
nuclear energy. You can feel heat and see light, but most energy, like electricity,
is invisible. We only see the result-like the lighting of a bulb.
All of the forms of energy we use come from the energy stored in natural
resources. Sunlight, water, wind, petroleum, coal, and natural gas are natural
resources. From these resources, we get heat, electricity, and mechanical power
to run machines.
IT STARTS WITH THE SUN
Most of our energy traces its source to the Sun. Inside the Sun, hydrogen atoms
join together and become helium. This process releases energy that radiates into
space in the form of waves. These waves give us heat and light.
Energy from the Sun is stored in plants and animals that we eat. Long before
humans existed, these ancient plants absorbed the Sun's energy, and animals
ate the plants as well as smaller animals. After the plants and animals died, they
got buried deeper and deeper underground. After millions of years, they turned
into coal and petroleum-what we call fossil fuels-that we are so dependent on
today, see WHY DO PLANTS NEED SUNLIGHT?.
HOMEWORK HELP:
The different forms of energy fall into two main categories. It helps to try and
picture each one:
Kinetic Energy is the energy of objects in motion. Water in a river, electricity in a
wire, and a sled going down a hill are good examples.
Potential Energy is the energy of objects that are not moving-but could move. If
you stretch a rubber band and hold it, it has potential energy. Let it go and its
potential energy changes to kinetic energy with a snap! Natural gas, coal, and
food are other examples of potential energy.
Title: ENERGY
Source: World Almanac for Kids, The
Date: January 1, 2006
Reading Level (Lexile): 790L
Copyright (c) 2006 The World Almanac for Kids by PRIMEDIA Reference Inc. The World
Almanac for Kids and Facto the Factosaurus are registered trademarks of PRIMEDIA Reference
Inc.
Record Number: 1108BBD494D00295