Energy
megaConverter #7
INFORMATION
PAGE
Introduction and
Overview
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Energy is the work done within a system. Or
the potential for such work. Work is defined as
applying a force through a certain distance. The
formula for energy is force x distance, or in the
case of kinetic energy, mass x velocity squared.
(Note that both formulas share the same set of
basic units) Thus, energy can be represented by
any force unit times any length unit, but few but
the common ones would have any practical
application.
Energy is a quantity that can be neither
formed nor destroyed, only changed from one form
to another.
There are three basic forms of energy:
kinetic, potential, and thermal. Kinetic energy
is the energy of motion. If you don’t think
there is energy in motion think of a car hitting
a tree. The kinetic energy of a moving object is
represented by ½ MV squared. Potential energy
represents forms such as chemical, atomic,
gravitational, material stress, etc. A boulder on
a mountaintop has potential energy because if it
falls off, it will accelerate and gain more and
more kinetic energy, until it hits the bottom
where the kinetic energy is transformed into heat
energy. The boulder falling is equivalent to work
because the gravity that causes the boulder to
fall is a force and it falls through a given
distance. Gasoline has potential energy because
it will burn and creates heat which can then be
transformed into kinetic energy which can be used
to do work. Atoms have potential energy because
they can be fissioned or fused in nuclear
reactors to produce heat which turns a steam
turbine which does work.
Energy was not a quantity people dealt with in
earlier times, and so the British and metric
units are the only ones in common use. This
megaConverter converts between the most commonly
used energy units of today.
For a more comprehensive treatment of
measurements, find "NTC’s Encyclopedia
of International Weights & Measures" by
William D. Johnstone at your local library. For a
better discussion of energy, see any college
physics textbook.
* Much of our written history still refers to
things in common units. The Bible does not refer
to meters or kilograms, but to cubits and stadia,
or shekels and drachma. Wouldn't it be nice to
know what they were talking about way back then?
Now you can use megaConverter! For a more
complete listing of ancient, foreign, and
obsolete measures, download our
'megaSpreadsheet' of conversions in MS Excel
format.
Glossary
of Conversions:
erg, joule, footpoundal,
footpound,
kilogram forcemeter
These are all direct units of
work. A force times a distance. The erg is the
name for the dynecentimeter. The joule is the
name for a newtonmeter.
kilocalorie
A calorie is the amount of energy
needed to raise the temperature of one gram of
water, at a specific temperature, one degree
Celsius. 1000 calories is a kilocalorie.
BTU
A BTU or British Thermal Unit is
the amount of energy needed to raise one
poundmass of pure water at a specific
temperature one degree Fahrenheit.
kilowatthour, horsepowerhour
Both are units commonly used to
measure cumulative power or the total energy
consumed by a mechanical or electrical system.
Use the formula:
energy = power x elapsed time.
Note: Because of roundoff
errors, converting from very large units to very
small units or viceversa may not be accurate (or
practical). Conversion factors can be found by
converting a quantity of 1 unit to another unit
several steps above or below the first. You may
need to string several conversion factors
together to find the factor from a very large
unit to a very small unit, and then you can use a
calculator with sufficient digits to find your
answer.
