What is thermal energy ?
Thermal Energy: A specialized term that refers to the part of the internal energy of a system which is the total present kinetic energy resulting from the random movements of atoms and molecules.
The ultimate source of thermal energy
available to mankind is the sun, the huge thermo-nuclear furnace that supplies
the earth with the heat and light that are essential to life. The nuclear fusion in the sun increases the sun's
thermal energy. Once the thermal energy leaves the sun (in the form of radiation) it is called heat.
Heat is thermal energy
in transfer. Thermal energy is part of the overall
internal energy of a system.
At a more basic level,
thermal energy comes form the movement of atoms and molecules in matter. It is a
form of kinetic energy produced from the random movements of those
molecules. Thermal energy of a system can be increased or decreased.
When you put your hand over a hot stove you can feel the heat. You are feeling thermal energy
in transfer.
The atoms and molecules in the metal of the burner are moving very rapidly because
the electrical energy from the wall outlet has increased the thermal energy in the burner.
We all know what happens when we rub our hands together. Our mechanical energy increases the thermal energy content of the atoms
in our hands and skin. We then
feel the consequence of this - heat.
Laws of Thermodynamics
When talking about thermal energy we must also
talk about the laws of thermodynamics which express the laws of the interaction of energy and matter.
First law of thermodynamics:
Energy and matter are interchangable but cannot be
created or destroyed. The total amount of energy in the whole universe remains
constant, only changing from one form to another.
Second Law of thermodynamics:
This law states that any system always tends to move
toward its probable state of energy. For example, a spring watch will run
until the potential energy in the spring is used up. If no new energy is
input into it (in the form of winding the spring up) then it has returned to
its most probable state, which is really not to run. The most misunderstood law.
Third Law of Thermodynamics:
This law is a little more complicated and
deals with the state of a system of atoms and molecules at an absolute zero
temperature. Absolute zero is theoretically impossible to achieve considering
any force acting upon the atoms and molecules to remove heat from them are not
at absolute zero and therefore cannot make anything else reach absolute
zero. The third law says that entropy of atoms and molecules at absolute zero
is zero.
