Kinetic Molecular Theory of Gases

Kinetic Molecular Theory of Gases The kinetic theory of gases is a scientific model that explains the physical behavior of a gas as the motion of the molecular particles that compose the gas. In this model, the submicroscopic particles (atoms or molecules) that make up the gas are continually moving around in random motion, constantly colliding not only with each other but also with the sides of any container that the gas is within. It is this motion that results in physical properties of the gas such as heat and pressure. The kinetic theory of gases is also called just the kinetic theory, or the kinetic model,  or the kinetic-molecular model. It can also in many ways be applied to fluids as well as gas. (The example of Brownian motion, discussed below, applies the kinetic theory to fluids.) History of the Kinetic Theory The Greek philosopher Lucretius was a proponent of an early form of atomism, though this was largely discarded for several centuries in favor of a physical model of gases built upon the non-atomic work of Aristotle. Without a theory of matter as tiny particles, the kinetic theory did not get developed within this Aristotlean framework. The work of Daniel Bernoulli presented the kinetic theory to a European audience, with his 1738 publication of Hydrodynamica. At the time, even principles like the conservation of energy had not been established, and so a lot of his approaches were not widely adopted. Over the next century, the kinetic theory became more widely adopted among scientists, as part of a growing trend toward scientists adopting the modern view of matter as composed of atoms. One of the lynchpins in experimentally confirming the kinetic theory, and atomism is general, was related to Brownian motion. This is the motion of a tiny particle suspended in a liquid, which under a microscope appears to randomly jerk about. In an acclaimed 1905 paper, Albert Einstein explained Brownian motion in terms of random collisions with the particles that composed the liquid. This paper was the result of Einsteins doctoral thesis work, where he created a diffusion formula by applying statistical methods to the problem. A similar result was independently performed by the Polish physicist Marian Smoluchowski, who published his work in 1906. Together, these applications of kinetic theory went a long way to support the idea that liquids and gases (and, likely, also solids) are composed of tiny particles. Assumptions of the Kinetic Molecular Theory The kinetic theory involves a number of assumptions that focus on being able to talk about an ideal gas. Molecules are treated as point particles. Specifically, one implication of this is that their size is extremely small in comparison to the average distance between particles.The number of molecules (N) is very large, to the extent that tracking individual particle behaviors is not possible. Instead, statistical methods are applied to analyze the behavior of the system as a whole.Each molecule is treated as identical to any other molecule. They are interchangeable in terms of their various properties. This again helps support the idea that individual particles dont need to be kept track of, and that the statistical methods of the theory are sufficient to arrive at conclusions and predictions.Molecules are in constant, random motion. They obey Newtons laws of motion.Collisions between the particles, and between the particles and walls of a container for the gas, are perfectly elastic collisions.Walls of containers of gases are treated as perfectly rigid, do not move, and are infinitely massive (in comparison to the particles). The result of these assumptions is that you have a gas within a container that moves around randomly within the container. When particles of the gas collide with the side of the container, they bounce off the side of the container in a perfectly elastic collision, which means that if they strike at a 30-degree angle, theyll bounce off at a 30-degree angle. The component of their velocity perpendicular to the side of the container changes direction but retains the same magnitude. The Ideal Gas Law The kinetic theory of gases is significant, in that the set of assumptions above lead us to derive the ideal gas law, or ideal gas equation, that relates the pressure (p), volume (V), and temperature (T), in terms of the Boltzmann constant (k) and the number of molecules (N). The resulting ideal gas equation is: pV NkT

Jury-rigged vs. Jerry-rigged

Jury-rigged vs. Jerry-rigged Jury-rigged vs. Jerry-rigged Jury-rigged vs. Jerry-rigged By Maeve Maddox A reader asks to know the difference between jury-rigged and jerry-rigged. Of the two, the older term is jury-rigged, a nautical term dating from the days of sail. Because they were often damaged in storms, sailing ships carried a spare mast called the jury-mast. Apart from scholarly speculation, the etymology of jury in this context is unknown. The jury-mast was like a spare tire, to be used only in an emergency and replaced by the real thing as soon as possible. The adjective jury-rigged came to be applied to anything intended to be of temporary use. Here are some examples of the term in current usage: Andrew Gill, had coolly waited for the weather to calm down after his vessel lost its mast and communications equipment in rough weather, and then jury-rigged a sail to get him to his destination.- SailWorld, 2012 Despite great hardship caused by limited power, loss of cabin heat, shortage of potable water, and the critical need to  jury-rig  the carbon dioxide removal system, the crew returned safely to  Earth  on April 17.- Princeton University site. A second expression that is earlier than jerry-rigged is jerry-built. As with the jury in jury-rigged, the origin of the jerry in jerry-built remains a mystery. First (1881) came the term jerry-builder: It is unfortunately too often the habit of builders- or rather jerry builders- to use the worst possible description of bricks. A jerry-builder was a contractor who put up shoddy houses for a quick sale. The first citation for the adjective jerry-built to describe shoddily built houses is dated 1869. Here are two recent examples of the use of jerry-built: In their need for access to varied sources of employment and cheap housing, immigrants were restricted to decaying or jerry-built housing.- The American Landscape, Stephen F. Mills, Routledge, 2013   Central to nearly all the semi-abstract paintings in â€Å"With a Tug and a Hold† are what appear to be architectural structures, or fragments of the built environment: a jerry-built wood shack here, a bit of metal scaffolding there.- The Washington Post, 2012. â€Å"Jerry-rigged† conflates â€Å"jury-rigged† with â€Å"jerry-built.† In American usage, jerry-rigged refers to something devised or repaired with materials at hand. Here are some examples: Our presentation was jerry-rigged because we hadn’t been able to get the software to work correctly in time.- The Accidental Millionaire, Gary Fong, BenBella Books, 2009. With the Afghan army also lagging in explosives experts, its members often resort to jerry-rigged tactics to locate and defuse IEDs, officials say.- The Washington Post, 2014 It was the very definition of jerry-rigged: She’d cut some slits in the back of a gel skin phone cover that would serve as credit card slots, taped a piece of cardboard on as a makeshift cover, and added a string to form a wristlet.- Huffington Post, 2014 Frustratingly, in this case, my attempt to use my iPad as a jerry-rigged solution has actually  created  problems I didn’t have before.  - MIT Technology Review, 2012. Although not in either the OED or Merriam-Webster, the verb to Macgyver is used with a similar meaning by some speakers: to Macgyver: to invent useful devices from ordinary materials. A device or mechanical solution created by Macgyvering is a Macgyverism. The words derive from the name of Angus MacGyver, a television character noted for his ability to resolve dangerous problems by non-violent means. Instead of a gun, this hero carries duct tape and a Swiss Army knife. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Expressions category, check our popular posts, or choose a related post below:50 Slang Terms for Money35 Genres and Other Varieties of Fiction30 Words for Small Amounts