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( Temperature)
In physics and thermodynamics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature. Specifically, temperature is a property of matter. Temperature is one of the principal parameters of thermodynamics. On the microscopic scale, temperature is defined as the average energy of microscopic motions of a single particle in the system per degree of freedom. On the macroscopic scale, temperature is the unique physical property that determines the direction of heat flow between two objects placed in thermal contact. If no heat flow occurs, the two objects have the same temperature; otherwise heat flows from the hotter object to the colder object. These two basic principles are stated in the zeroth law and second law of thermodynamics, respectively. For a solid, these microscopic motions are principally the vibrations of its atoms about their sites in the solid. For an ideal monatomic gas, the microscopic motions are the translational motions of the constituent gas particles. For a multiatomic gas, vibrational and rotational motion should be included Temperature is measured with thermometers that may be calibrated to a variety of temperature scales. In most of the world (except for the United States, and a few other countries[which?]), the degree Celsius scale is used for most temperature measuring purposes. The entire scientific world (the U.S. included) measures temperature using the Celsius scale and thermodynamic temperature using the kelvin scale, which is just the Celsius scale shifted downwards so that 0 K[1]= -273.15 °C, or absolute zero. Many engineering fields in the U.S., especially high-tech ones, also use the kelvin and degrees Celsius scales. However, the United States is the last major country[citation needed] in which the degree Fahrenheit temperature scale is used by most lay people, industry, popular meteorology, and government. Other engineering fields in the U.S. also rely upon the Rankine scale (a shifted Fahrenheit scale) when working in thermodynamic-related disciplines such as combustion. Intuitively, temperature is the measurement of how hot or cold something is, although the most immediate way in which we can measure this, by feeling it, is unreliable, resulting in the phenomenon of felt air temperature, which can differ at varying degrees from actual temperature. On the molecular level, temperature is the result of the motion of particles which make up a substance. Temperature increases as the energy of this motion increases. The motion may be the translational motion of the particle, or the internal energy of the particle due to molecular vibration or the excitation of an electron energy level. Although very specialized laboratory equipment is required to directly detect the translational thermal motions, thermal collisions by atoms or molecules with small particles suspended in a fluid produces Brownian motion that can be seen with an ordinary microscope. The thermal motions of atoms are very fast and temperatures close to absolute zero are required to directly observe them. For instance, when scientists at the NIST achieved a record-setting cold temperature of 700 nK (1 nK = 10-9 K) in 1994, they used optical lattice laser equipment to adiabatically cool caesium atoms. They then turned off the entrapment lasers and directly measured atom velocities of 7 mm per second in order to calculate their temperature. The process of cooling involves removing energy from a system. When there is no more energy able to be removed, the system is said to be at absolute zero, which is the point on the thermodynamic (absolute) temperature scale where all kinetic motion in the particles comprising matter ceases and they are at complete rest in the “classic” (non-quantum mechanical) sense. By definition, absolute zero is a temperature of precisely 0&_160;kelvins (-273.15 °C or -459.68 °F).
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Temperature Subcategories
Temperature Articles
Soothe Arthritis Pain with Hot and Cold Temperatures by Russ Anderson
Arthritis pain suffers have a number of different treatment options to help reduce the pain and stiffness of arthritis. The use of heat and cold treatments has long been a well-known natural treatment for arthritis pain. Each temperature, hot or cold...
Choose the Right Oil to Fight Thyroid Disease by John Goh
The thyroid gland is one of the larger endocrine glands in the body. It is a double-lobed structure located in the neck and produces hormones, principally thyroxine (T4) and triiodothyronine (T3). These hormones regulate the rate of metabolism ...
Sleep and Body Temperature - The Connection by Wendy Owen
There is a definite relationship between our core body temperature and our feelings of lethargy or energy. When the body is warm, we feel wide awake. When the body is cool, feeling of tiredness and sleepiness prevail.
Not everybody realizes...
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