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Mpemba Effect
The Mpemba effect is the name given to the observation that a liquid (typically water) which is initially hot can freeze faster than the same liquid which begins cold, under otherwise similar conditions. There is disagreement about its theoretical basis and the parameters required to produce the effect. The Mpemba effect is named after Tanzanian schoolboy Erasto Bartholomeo Mpemba (1950–2020) whose story of it in 1963 became highly popularized. The discovery and noted observations of it, however, originate in ancient times, having been said by Aristotle to be common knowledge. Definition The phenomenon, when taken to mean "hot water freezes faster than cold", is difficult to reproduce or confirm because this statement is ill-defined. Monwhea Jeng has proposed a more precise wording: "There exists a set of initial parameters, and a pair of temperatures, such that given two bodies of water identical in these parameters, and differing only in initial uniform temperatures, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observation
Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. The term may also refer to any data collected during the scientific activity. Observations can be qualitative, that is, only the absence or presence of a property is noted, or quantitative if a numerical value is attached to the observed phenomenon by counting or measuring. Science The scientific method requires observations of natural phenomena to formulate and test hypotheses. It consists of the following steps: # Ask a question about a natural phenomenon # Make observations of the phenomenon # Formulate a hypothesis that tentatively answers the question # Predict logical, observable consequences of the hypothesis that have not yet been investigated # Test the hypothesis' predictions by an experiment, observational study, field study ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daniel Gabriel Fahrenheit
Daniel Gabriel Fahrenheit FRS (; ; 24 May 1686 – 16 September 1736) was a physicist, inventor, and scientific instrument maker. Born in Poland to a family of German extraction, he later moved to the Dutch Republic at age 15, where he spent the rest of his life (1701–1736). A pioneer of exact thermometry, he helped lay the foundations for the era of precision thermometry by inventing the mercury-in-glass thermometer and Fahrenheit scale.Encyclopædia Britannica"Science & Technology: Daniel Gabriel Fahrenheit" /ref> Biography Fahrenheit was born in Danzig (Gdańsk), then in the Polish–Lithuanian Commonwealth, but lived most of his life in the Dutch Republic. The Fahrenheits were a German Hanse merchant family who had lived in several Hanseatic cities. Fahrenheit's great-grandfather had lived in Rostock, and research suggests that the Fahrenheit family originated in Hildesheim. Daniel's grandfather moved from Kneiphof in Königsberg (present-day Kaliningrad) to Danzig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell–Boltzmann Distribution
In physics (in particular in statistical mechanics), the Maxwell–Boltzmann distribution, or Maxwell(ian) distribution, is a particular probability distribution named after James Clerk Maxwell and Ludwig Boltzmann. It was first defined and used for describing particle speeds in idealized gases, where the particles move freely inside a stationary container without interacting with one another, except for very brief collisions in which they exchange energy and momentum with each other or with their thermal environment. The term "particle" in this context refers to gaseous particles only ( atoms or molecules), and the system of particles is assumed to have reached thermodynamic equilibrium.''Statistical Physics'' (2nd Edition), F. Mandl, Manchester Physics, John Wiley & Sons, 2008, The energies of such particles follow what is known as Maxwell–Boltzmann statistics, and the statistical distribution of speeds is derived by equating particle energies with kinetic energy. Mathema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distribution Function (physics)
:''This article describes the ''distribution function'' as used in physics. You may be looking for the related mathematical concepts of cumulative distribution function or probability density function.'' In molecular kinetic theory in physics, a system's distribution function is a function of seven variables, f(x,y,z,t;v_x,v_y,v_z), which gives the number of particles per unit volume in single-particle phase space. It is the number of particles per unit volume having approximately the velocity \mathbf=(v_x,v_y,v_z) near the position \mathbf=(x,y,z) and time t. The usual normalization of the distribution function is :n(x,y,z,t) = \int f \,dv_x \,dv_y \,dv_z, :N(t) = \int n \,dx \,dy \,dz, where, ''N'' is the total number of particles, and ''n'' is the number density of particles – the number of particles per unit volume, or the density divided by the mass of individual particles. A distribution function may be specialised with respect to a particular set of dimensions. E.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granular Material
A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when grains collide). The constituents that compose granular material are large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1 μm. On the upper size limit, the physics of granular materials may be applied to ice floes where the individual grains are icebergs and to asteroid belts of the Solar System with individual grains being asteroids. Some examples of granular materials are snow, nuts, coal, sand, rice, coffee, corn flakes, fertilizer, and bearing balls. Research into granular materials is thus directly applicable and goes back at least to Charles-Augustin de Coulomb, whose law of friction was originally stated for granular materials. Granular materials are commercially important in appli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ising Model
The Ising model () (or Lenz-Ising model or Ising-Lenz model), named after the physicists Ernst Ising and Wilhelm Lenz, is a mathematical model of ferromagnetism in statistical mechanics. The model consists of discrete variables that represent magnetic dipole moments of atomic "spins" that can be in one of two states (+1 or −1). The spins are arranged in a graph, usually a lattice (where the local structure repeats periodically in all directions), allowing each spin to interact with its neighbors. Neighboring spins that agree have a lower energy than those that disagree; the system tends to the lowest energy but heat disturbs this tendency, thus creating the possibility of different structural phases. The model allows the identification of phase transitions as a simplified model of reality. The two-dimensional square-lattice Ising model is one of the simplest statistical models to show a phase transition. The Ising model was invented by the physicist , who gave it as a prob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Scientist
''New Scientist'' is a magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publishes a monthly Dutch-language edition. First published on 22 November 1956, ''New Scientist'' has been available in online form since 1996. Sold in retail outlets (paper edition) and on subscription (paper and/or online), the magazine covers news, features, reviews and commentary on science, technology and their implications. ''New Scientist'' also publishes speculative articles, ranging from the technical to the philosophical. ''New Scientist'' was acquired by Daily Mail and General Trust (DMGT) in March 2021. History Ownership The magazine was founded in 1956 by Tom Margerison, Max Raison and Nicholas Harrison as ''The New Scientist'', with Issue 1 on 22 November 1956, priced at one shilling (a twentieth of a pound in pre-decimal UK ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics World
''Physics World'' is the membership magazine of the Institute of Physics, one of the largest physical societies in the world. It is an international monthly magazine covering all areas of physics, pure and applied, and is aimed at physicists in research, industry, physics outreach, and education worldwide. Overview The magazine was launched in 1988 by IOP Publishing Ltd, under the founding editorship of Philip Campbell. The magazine is sent free to members of the Institute of Physics, who can access a digital edition of the magazine; selected articles can be read by anyone for free online. It was redesigned in September 2005 and has an audited circulation of just under 35000. The current editor is Matin Durrani. Others on the team are Michael Banks (news editor) and Tushna Commissariat and Sarah Teah (features editors). Hamish Johnston, Margaret Harris and Tami Freeman are online editors. Alongside the print and online magazine, Physics World produces films and two podcasts. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Journal Of Physics
The ''American Journal of Physics'' is a monthly, peer-reviewed scientific journal published by the American Association of Physics Teachers and the American Institute of Physics. The editor-in-chief is Beth Parks of Colgate University."Current Frequency: Monthly, 2002; and Former Frequency varies, 1940-2001" Confirmation of Editor, ISSN, CODEN, and other relevant information. Aims and scope The focus of this journal is undergraduate and graduate level physics. The intended audience is college and university physics teachers and students. Coverage includes current research in physics, instructional laboratory equipment, laboratory demonstrations, teaching methodologies, lists of resources, and book reviews. In addition, historical, philosophical and cultural aspects of physics are also covered. According to the 2021 Journal Citation Reports from Clarivate, this journal has a 2020 impact factor of 1.022. History The former title of this journal was ''American Physics Teache ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
College Of African Wildlife Management
The College of African Wildlife Management (CAWM), commonly known as Mweka College or just Mweka, is located near the village of that name on the southern slopes of Mount Kilimanjaro in Tanzania, above the city of Moshi, about 14 kilometres north of its centre. The locality also gives its name to the Mweka Trail, one of the routes on Kilimanjaro, used for the descent. Following the independence of Tanganyika in 1961, the College of African Wildlife Management was established in 1963 by Bruce Kinloch as a pioneer institution for the training of African wildlife managers. Initial funding for Mweka was provided by the African Wildlife Leadership Foundation (now known as the African Wildlife Foundation), the U.S. Agency for International Development, and the Frankfurt Zoological Society, with facilities donated by the government of Tanganyika. Since this time, the College has trained over 5,000 wildlife managers from 52 countries worldwide (28 African countries and 24 other countr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dar Es Salaam
Dar es Salaam (; from ar, دَار السَّلَام, Dâr es-Selâm, lit=Abode of Peace) or commonly known as Dar, is the largest city and financial hub of Tanzania. It is also the capital of Dar es Salaam Region. With a population of over six million people, Dar is the largest city in East Africa and the seventh-largest in Africa. Located on the Swahili coast, Dar es Salaam is an important economic centre and is one of the fastest-growing cities in the world. The town was founded by Majid bin Said, the first Sultan of Zanzibar, in 1865 or 1866. It was the main administrative and commercial center of German East Africa, Tanganyika, and Tanzania. The decision was made in 1974 to move the capital to Dodoma and was officially completed in 1996. Dar es Salaam is Tanzania's most prominent city for arts, fashion, media, film, television, and finance. It is the capital of the co-extensive Dar es Salaam Region, one of Tanzania's 31 administrative regions, and consists of five dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denis Osborne
Denis Gordon Osborne (17 September 1932 – 3 September 2014) was a British diplomat and academic. Early life Osborne was educated at Dr Challoner's Grammar School in Amersham and University College, Durham, where he graduated with a first-class degree in Physics in 1953. He completed a PhD at the same institution. Career From 1957 he was a Durham University lecturer in Physics, including a period in 1958 lecturing in Sierra Leone at Fourah Bay College - then affiliated with Durham. He stayed in Africa and became Senior Lecturer in Physics at the University of Ghana, but was eventually arrested and imprisoned by the government of Kwame Nkrumah. In 1964 he joined the University of Dar es Salaam as Reader in Physics, becoming Professor in 1966 and Dean of Science in 1968. After a student in a physics lecture, Erasto Mpemba, asked him why hot water sometimes freezes faster than cold water, Osborne experimented to confirm Mpemba's observation, and together they co-authored a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
