LAW OF CONSERVATION OF ENERGY
Energy, Work, and Power
CP-05
Page 6
Rev. 0
LAW OF CONSERVATION OF ENERGY
Energy does not simply appear and disappear. Energy is transferred from one position
to another or transformed from one type of energy to another.
EO 1.4
STATE the First Law of Thermodynamics, "Conservation
of Energy."
Conservation of Energy
The First Law of Thermodynamics is simply stated "energy cannot be created or destroyed, only
altered in form." In the previous chapter, we discussed potential energy, where a force is applied
to an object, raising it from some point of origin to some height. The energy expended in raising
the object is equivalent to the potential energy gained by the object because of its height. This
is an example of a transfer of energy as well as an alteration of the type of energy. Another
example is throwing a baseball. While the ball is in your hand, it contains no kinetic energy.
You apply a force to the ball by throwing it. The ball leaves your hand with a velocity, giving
it kinetic energy equal to the work applied by your hand. Mathematically, this can be described
by the following simplified equation.
Energy
+ Energy
- Energy
= Energy
(5-4)
initial
added
removed
final
where:
Energy
is energy initially stored in an object/substance. This energy can exist in
initial
various combinations of kinetic energy and potential energy.
Energy
is energy added to the object/substance. Heat can be added. Energy can be
added
added in the form of stored energy in any mass added, such as water to a fluid system.
Work can be done on a system. Heat is energy gained or lost at a microscopic level.
Work is the same at a macroscopic level.
Energy
is energy removed from an object/substance. Heat can be rejected. Work
removed
can be done by the system. This energy can be in the form of energy stored in any mass
removed.
Energy
is energy remaining within the object/substance after all energy transfers and
final
transformations occur. This energy can exist in various combinations of kinetic,
potential, flow, and internal energy.
