Kinetics (physics)
{{short description|Subfield of physics}}
{{Distinguish|Kinematics}}
{{Use dmy dates|date=December 2015}}
{{Classical mechanics|cTopic=Branches}}
In physics and engineering, kinetics is the branch of classical mechanics that is concerned with the relationship between the motion and its causes, specifically, forces and torques.[http://www.britannica.com/EBchecked/topic/318197/kinetics kinetics]. Encyclopædia Britannica Online.{{cite book |title=Text-book of Mechanics |author=Louis Adolphe Martin |page=Section X, pp. 69ff |url=https://books.google.com/books?id=Pr43AAAAMAAJ&pg=PA67|year=1907 |publisher=Wiley}}Kinetics must not be confused with kinematics, the study of motion without consideration of the physical circumstances causing it (see, e.g., {{cite book |edition=Reprint of the Fourth Edition of 1936 with a foreword by William McCrea |title=A Treatise on the Analytical Dynamics of Particles and Rigid Bodies |author=Edmund Taylor Whittaker|author-link=E. T. Whittaker |page=Chapter 1 |year=1988 |publisher=Cambridge University Press |isbn=0-521-35883-3}}), which is a separate branch of classical mechanics. Since the mid-20th century, the term "dynamics" (or "analytical dynamics") has largely superseded "kinetics" in physics textbooks,See this discussion. though the term is still used in engineering.
In plasma physics, kinetics refers to the study of continua in velocity space. This is usually in the context of non-thermal (non-Maxwellian) velocity distributions, or processes that perturb thermal distributions. These "kinetic plasmas" cannot be adequately described with fluid equations.
The term kinetics is also used to refer to chemical kinetics, particularly in chemical physics and physical chemistry.
{{Cite book
| isbn = 0-7506-2635-6
| last1 = Lifshitz
| first1 = E. M.
| author-link=Evgeny Lifshitz
| first2 = L. P. | last2 = Pitaevskii | first3 = J. B. | last3= Sykes |first4 = R.N. | last4 = Franklin
| title = Physical Kinetics
| publisher=Butterworth-Heinemann
| year = 1981
{{Cite book
| isbn = 0-444-51582-8
| last = Alexeev
| first = Boris V.
|author2=Alexeev
| title = Generalized Boltzmann Physical Kinetics
| publisher=Elsevier
| year = 2004
{{Cite book
| isbn = 1-56700-044-4
| last = Gorelik
| first = G. E.
|author2=N. V. Pavlyukevish |author3=V. V. Levdansky |author4=V. G. Leitsina |author5=G. I. Rudin
| title = Physical Kinetics and Transfer Processes in Phase Transitions
| publisher=Begell House
| year = 1995
{{Cite book
| isbn = 0-88318-953-4
| last = Krainov
| first = Vladimir P.
|author2=Kevin Hendzel
| title = Qualitative Methods in Physical Kinetics and Hydrodynamics
| publisher=Springer
| year = 1992
{{Cite book
| last = American Chemical Society
| first = Division of Physical Chemistry
| publisher = American Chemical Society
| title = Evolution of Kinetics: A Centennial Symposium of the Division of Physical Chemistry, American Chemical Society
| year = 1976
{{cite journal
| url=https://doi.org/10.1007/s11661-016-3874-z
| vauthors=Alvarenga HD, Van Steenberge N, Sietsma J, Terryn H
| title=The Kinetics of Formation and Decomposition of Austenite in Relation to Carbide Morphology
| journal=Metall Mater Trans A
| date= Feb 2017 |volume=48
| pages=828–840
|doi=10.1007/s11661-016-3874-z| url-access=subscription}} In such uses, a qualifier is often used or implied, for example: "physical kinetics", "crystal growth kinetics", and so on.