Thermodynamics Overview

Specifically, thermodynamics focuses largely on how a heat transfer is related to various energy changes within a physical system undergoing a thermodynamic process. Such processes usually result in work being done by the system and are guided by the laws of thermodynamics.

• Thermal Contact is when two substances can affect each other's temperature.
• Thermal Equilibrium is when two substances in thermal contact no longer transfer heat.
• Thermal Expansion takes place when a substance expands in volume as it gains heat. Thermal contraction also exists.
• Conduction is when heat flows through a heated solid.
• Convection is when heated particles transfer heat to another substance, such as cooking something in boiling water.
• Radiation is when heat is transferred through electromagnetic waves, such as from the sun.
• Insulation is when a low-conducting material is used to prevent heat transfer.

There are several specific types of thermodynamic processes that have special properties:

• Adiabatic process - a process with no heat transfer into or out of the system.
• Isochoric process - a process with no change in volume, in which case the system does no work.
• Isobaric process - a process with no change in pressure.
• Isothermal process - a process with no change in temperature.

The 5 states of matter

• gas
• liquid
• solid
• plasma
• superfluid (such as a Bose-Einstein Condensate)

Phase Transitions

• condensation - gas to liquid
• freezing - liquid to solid
• melting - solid to liquid
• sublimation - solid to gas
• vaporization - liquid or solid to gas

C = delta-Q / delta-T

Boyle's Law (T is constant):
P₁V₁ = P₂V₂

Charles/Gay-Lussac Law (P is constant):
V₁/T₁ = V₂/T₂

Ideal Gas Law:
P₁V₁/T₁ = P₂V₂/T₂ = nR

• Zeroeth Law of Thermodynamics - Two systems each in thermal equilibrium with a third system are in thermal equilibrium to each other.
• First Law of Thermodynamics - The change in the energy of a system is the amount of energy added to the system minus the energy spent doing work.
• Second Law of Thermodynamics - It is impossible for a process to have as its sole result the transfer of heat from a cooler body to a hotter one.
• Third Law of Thermodynamics - It is impossible to reduce any system to absolute zero in a finite series of operations. This means that a perfectly efficient heat engine cannot be created.

In any closed system, the entropy of the system will either remain constant or increase.

That having been said, there are some fields use thermodynamics in passing as they go about studying other phenomena, while there are a wide range of fields which focus heavily on the thermodynamics situations involved. Here are some of the sub-fields of thermodynamics:

• Cryophysics / Cryogenics / Low Temperature Physics - the study of physical properties in low temperature situations, far below temperatures experienced on even the coldest regions of the Earth. An example of this is the study of superfluids.

• Fluid Dynamics / Fluid Mechanics - the study of the physical properties of "fluids," specifically defined in this case to be liquids and gases.

• High Pressure Physics - the study of physics in extremely high pressure systems, generally related to fluid dynamics.

• Meteorology / Weather Physics - the physics of the weather, pressure systems in the atmosphere, etc.

• Plasma Physics - the study of matter in the plasma state.