According to the second law of thermodynamics, when energy
is converted from one form to another, some of it is degraded into heat, a less
usable form that disperses into the environment.
Examples of the second law of thermodynamics:
A 1000 Watt electrical heater uses 1000 J/sec of electrical
energy. If it is 60% efficient, then the
heater converts 60% of the electrical energy into heating water and 40% is
wasted by being transformed into heat.
-The 60% efficiency (40% waste) increasing disorder.
-This is the law of increasing entropy. It states that the
entropy of the universe increases with every physical process (change) that
occurs. Entropy refers to the level of disorder, randomness, or chaos, of a
system. The higher the randomness of a system, the higher its entropy. The more
organized a system, the lower its entropy.
As a result of the second law of thermodynamics, no process
requiring an energy conversion is ever 100% efficient because much of the
energy is dispersed as heat, resulting in an increase in entropy. An automobile
engine, which converts the chemical energy of gasoline to mechanical energy, is
between 20 and 30% efficient. That is, only 20 to 30% of the original energy
stored in the chemical bonds of the gasoline molecules is actually transformed
into mechanical energy, or work.
Why is the second law
of thermodynamics necessary? Why isn’t
the first law of thermodynamics enough?
The first law of thermodynamics is just a
statement of the law of conservation of energy.
But there are many processes which obey the law of conservation of
energy, that we never see happen. For
example, we never see a glass of water sitting on the counter cool down and
start freezing in one half while the other half heats up and boils. This would be possible according to the law
of conservation of energy as long as the energy lost by the freezing water is
equal to the energy gained by the boiling water. The second law of thermodynamics is there to
explain why such events never happen in our experience.