CONSERVATION OF ENERGY
Though energy
can be converted from one form to another, energy cannot be
created or destroyed. This principle is called the "law
of conservation of energy." For example, in a motorcycle,
the chemical potential energy of the fuel changes to kinetic
energy. In a radio, electricity is converted into kinetic
energy and wave energy (sound).
Machines can
be used to convert energy from one form to another. Though
ideal machines conserve the mechanical energy of a system,
some of the energy always turns into heat when using a machine.
For example, heat generated by friction is hard to collect
and transform into another form of energy. In this situation,
heat energy is usually considered unusable or lost.
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