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Conservation
of Energy
 Energy
is neither created or destroyed but only changes form (transforms).
All of the energy that goes into a system is constant. In other
words, energy may be converted from one form to another, but it
doesn't just disappear or multiply. For example, let's say we are
going to turn natural gas into electricity. We want to look where
the energy goes during the process of turning it into electricity.
1. The natural
gas is burned, creating heat energy.
2. The heat energy is used to turn water into steam.
3. The steam turns a turbine generator. This changes the heat energy
into mechanical energy. Finally, the mechanical energy used by the
generator makes electrical energy.
We only wanted
one type of energy — electricity. But the process can't turn
natural gas directly into electricity. Energy was used during the
process. We lost energy as extra heat, friction (created by the
turbine), and products of combustion (smoke, carbon dioxide, water).
In the end, the natural gas that is combusted is equal to all of
the other forms of energy that it was transformed into.
Potential
and Kinetic Energy
All energy is either
or .
Potential
Energy
 Potential
energy is energy that is in a stored form. It isn't being used at
the moment, but is waiting to do work. Think about a boulder sitting
on top of a hill. Just sitting there, the boulder isn't doing anything.
But because it is sitting on top of a hill, it has the potential
to roll down and do some damage to a car or building below. The
energy is stored in that rock because of its size (mass) and the
distance it will travel once it starts rolling.
Kinetic Energy
 Kinetic
energy is energy that is in motion. This energy is performing work.
Legs are pumping bicycle pedals. Coal is running generators. Lightning
is snapping trees.
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