Thermodynamics is the study of how heat can be transformed into useful energy in the form of work, hence the name thermo + dynamics. It is an extremely vast and intricate area of science which took many years to develop, beginning in the early 19th century. Scientists were beginning to understand the possibility of attaining work from a heat source, and this was first demonstrated by James Joule in the 1840's. Thermodynamics gives the foundation for heat engines, power plants, chemical reactions, refrigerators, and many more important concepts that the world we live in today relies on.
Beginning to understand thermodynamics requires knowledge of how the microscopic world operates. Some key ideas that describe the microscopic properties of a system include temperature, pressure and internal energy. Understanding the properties of a system is crucial, but even more so is the transfer of this energy to other systems, known as heat transfer. An analysis of these ideas led scientists to the formulation of the four laws of thermodynamics.
Laws of Thermodynamics
The laws of thermodynamics lay the foundation for how a system can change, function, and supply useful energy. They are all fundamental statements to all of science, and introduce important concepts which extend far beyond the bounds of the topic. These statements are introduced below, and can be explored fully on their respective pages:
- The zeroth law of thermodynamics - this law is a statement of thermal equilibrium and what that means for heat transfer. This is a way of thinking about what it means for two systems to be at the same temperature.
- The first law of thermodynamics - this is essentially the law of conservation of energy, but states that the change internal energy is given by an input of heat, work, or both.
- The second law of thermodynamics - this law imposes more severe constraints on heat transfer and limits the efficiency of heat engines. It introduces the important idea of entropy, which has some interesting implications.
- The third law of thermodynamics - the idea of absolute zero is introduced, and this law shows that nothing can be cooled to this temperature.
- geograph UK [Online], Available: http://upload.wikimedia.org/wikipedia/commons/7/74/Sommerfeld1897.gif
- Randall Knight, Physics for Scientists and Engineers, 3rd Ed. New York: Pearson, 2013, Ch. 16, p. 443.
- Waterloo University, Historical Background [Online], Available: http://www.mhtl.uwaterloo.ca/courses/me354/past.html
- Image of A. Sommerfeld via Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/7/74/Sommerfeld1897.gif
- B. Everett, G. Boyle, S. Peake and J. Ramage, "Heat to motive power," in Energy Systems and Sustainability, 2nd ed., Oxford, UK: Oxford, 2013, ch.6, pp.187