Laws of Thermodynamics
The laws of thermodynamics are fundamental truths based on the study of
energy exchanges between a system
and its surroundings. The first law of thermodynamics states that
energy can only be converted from one state to another, but cannot
be created or destroyed. Energy referred to here is that of work,
heat, and internal energy. Work is done when a force acts through a
distance and the transfer of energy from the
system to
its surroundings results. Heat is an energy transfer which takes place
when two regions of different temperatures are connected by a thermal
conductor. Internal energy refers to the energy stored in a body,
and is therefore equal to the heat flow into the system minus the
work done by the system on its surroundings.
"The second law of thermodynamics states that heat, on its own
accord, flows from regions of high temperatures to regions of low
temperatures". When applying the law to heat engines, it can be
stated that no heat engine can be 100% efficient.
When looking at the two laws together, it is noted that energy is
being constantly degraded; in a thermodynamic process there is always
less energy available for doing work, not more. This leads to the
definition of entropy which always increases as energy becomes less
available for doing work.(Eblen and Eblen, 1994, p. 185)
Compiled by
Joy Grillon jg2@cec.wustl.edu Last updated 10/27/94.