“temperature”的概念、定义、翻译、参考文献-科学参考

temperature

Physics

The property of a body or region of space that determines whether or not there will be a net flow of heat into it or out of it from a neighbouring body or region and in which direction (if any) the heat will flow. If there is no heat flow the bodies or regions are said to be in thermodynamic equilibrium and at the same temperature. If there is a flow of heat, the direction of the flow is from the body or region of higher temperature. Broadly, there are two methods of quantifying this property. The empirical method is to take two or more reproducible temperature-dependent events and assign fixed points on a scale of values to these events. For example, the Celsius temperature scale uses the freezing point and boiling point of water as the two fixed points, assigns the values 0 and 100 to them, respectively, and divides the scale between them into 100 degrees. This method is serviceable for many practical purposes (see temperature scales), but lacking a theoretical basis it is awkward to use in many scientific contexts. In the 19th century, Lord Kelvin proposed a thermodynamic method to specify temperature, based on the measurement of the quantity of heat flowing between bodies at different temperatures. This concept relies on an absolute scale of temperature with an absolute zero of temperature, at which no body can give up heat. He also used Sadi Carnot’s concept of an ideal frictionless perfectly efficient heat engine (see Carnot cycle). This Carnot engine takes in a quantity of heat q₁ at a temperature T₁, and exhausts heat q₂ at T₂, so that T₁/T₂=q₁/q₂. If T₂ has a value fixed by definition, a Carnot engine can be run between this fixed temperature and any unknown temperature T₁, enabling T₁ to be calculated by measuring the values of q₁ and q₂. This concept remains the basis for defining thermodynamic temperature, quite independently of the nature of the working substance. The unit in which thermodynamic temperature is expressed is the kelvin. In practice thermodynamic temperatures cannot be measured directly; they are usually inferred from measurements with a gas thermometer containing a nearly ideal gas. This is possible because another aspect of thermodynamic temperature is its relationship to the internal energy of a given amount of substance. This can be shown most simply in the case of an ideal monatomic gas, in which the internal energy per mole (U) is equal to the total kinetic energy of translation of the atoms in one mole of the gas (a monatomic gas has no rotational or vibrational energy). According to kinetic theory, the thermodynamic temperature of such a gas is given by T = 2U/3R, where R is the universal gas constant.

Mathematics

A physical property of matter that quantitatively measures hotness, usually on the Celsius or Kelvin scales. It is a scalar quantity whose gradient determines heat flux (see Fourier’s law), and the heat in a given body will be in proportion to its temperature. See also heat equation, Newton’s law of cooling.

Astronomy

A measurement of the heat energy possessed by a body. Temperature can be measured in various ways, such as the total energy emitted (effective temperature), its emission at a single frequency (colour temperature), the mean velocity of the particles (kinetic temperature), the levels of excitation of electrons in atoms (excitation temperature), or degree of ionization (ionization temperature). In thermal equilibrium all measures of temperature will give the same value, but under other conditions they may give quite different temperatures. The kelvin scale is used for scientific measurements of temperature.

Chemistry

The property of a body or region of space that determines whether or not there will be a net flow of heat into it or out of it from a neighbouring body or region and in which direction (if any) the heat will flow. If there is no heat flow the bodies or regions are said to be in thermodynamic equilibrium and at the same temperature. If there is a flow of heat, the direction of the flow is from the body or region of higher temperature. Broadly, there are two methods of quantifying this property. The empirical method is to take two or more reproducible temperature-dependent events and assign fixed points on a scale of values to these events. For example, the Celsius temperature scale uses the freezing point and boiling point of water as the two fixed points, assigns the values 0 and 100 to them, respectively, and divides the scale between them into 100 degrees. This method is serviceable for many practical purposes (see temperature scales), but lacking a theoretical basis it is awkward to use in many scientific contexts. In the 19th century, Lord Kelvin proposed a thermodynamic method to specify temperature, based on the measurement of the quantity of heat flowing between bodies at different temperatures. This concept relies on an absolute scale of temperature with an absolute zero of temperature, at which no body can give up heat. He also used Sadi Carnot’s concept of an ideal frictionless perfectly efficient heat engine (see Carnot cycle). This Carnot engine takes in a quantity of heat q₁ at a temperature T, and exhausts heat q₂ at T₂, so that T₁/T₂ = q₁/q₂. If T₂ has a value fixed by definition, a Carnot engine can be run between this fixed temperature and any unknown temperature T₁, enabling T₁ to be calculated by measuring the values of q₁ and q₂. This concept remains the basis for defining thermodynamic temperature, quite independently of the nature of the working substance. The unit in which thermodynamic temperature is expressed is the kelvin. In practice thermodynamic temperatures cannot be measured directly; they are usually inferred from measurements with a gas thermometer containing a nearly ideal gas. This is possible because another aspect of thermodynamic temperature is its relationship to the internal energy of a given amount of substance. This can be shown most simply in the case of an ideal monatomic gas, in which the internal energy per mole (U) is equal to the total kinetic energy of translation of the atoms in one mole of the gas (a monatomic gas has no rotational or vibrational energy). According to kinetic theory, the thermodynamic temperature of such a gas is given by T = 2U/3R, where R is the universal gas constant.

Chemical Engineering

A measure of the intensity of heat that will flow into or out of a body or medium from another body or medium, and in which direction the heat flows. As a physical property of a body, it is proportional to the kinetic energy of the atoms or molecules. Where there is no heat flow, the body or medium is in thermodynamic equilibrium and at the same temperature as the other body or medium. Where they are not in equilibrium, the heat flows in the direction of the higher to the lower temperature body. There are various temperature scales used to quantify the property of temperature including kelvin, centigrade or Celsius, and Fahrenheit scales.

单词	temperature
释义	temperature Physics The property of a body or region of space that determines whether or not there will be a net flow of heat into it or out of it from a neighbouring body or region and in which direction (if any) the heat will flow. If there is no heat flow the bodies or regions are said to be in thermodynamic equilibrium and at the same temperature. If there is a flow of heat, the direction of the flow is from the body or region of higher temperature. Broadly, there are two methods of quantifying this property. The empirical method is to take two or more reproducible temperature-dependent events and assign fixed points on a scale of values to these events. For example, the Celsius temperature scale uses the freezing point and boiling point of water as the two fixed points, assigns the values 0 and 100 to them, respectively, and divides the scale between them into 100 degrees. This method is serviceable for many practical purposes (see temperature scales), but lacking a theoretical basis it is awkward to use in many scientific contexts. In the 19th century, Lord Kelvin proposed a thermodynamic method to specify temperature, based on the measurement of the quantity of heat flowing between bodies at different temperatures. This concept relies on an absolute scale of temperature with an absolute zero of temperature, at which no body can give up heat. He also used Sadi Carnot’s concept of an ideal frictionless perfectly efficient heat engine (see Carnot cycle). This Carnot engine takes in a quantity of heat q₁ at a temperature T₁, and exhausts heat q₂ at T₂, so that T₁/T₂=q₁/q₂. If T₂ has a value fixed by definition, a Carnot engine can be run between this fixed temperature and any unknown temperature T₁, enabling T₁ to be calculated by measuring the values of q₁ and q₂. This concept remains the basis for defining thermodynamic temperature, quite independently of the nature of the working substance. The unit in which thermodynamic temperature is expressed is the kelvin. In practice thermodynamic temperatures cannot be measured directly; they are usually inferred from measurements with a gas thermometer containing a nearly ideal gas. This is possible because another aspect of thermodynamic temperature is its relationship to the internal energy of a given amount of substance. This can be shown most simply in the case of an ideal monatomic gas, in which the internal energy per mole (U) is equal to the total kinetic energy of translation of the atoms in one mole of the gas (a monatomic gas has no rotational or vibrational energy). According to kinetic theory, the thermodynamic temperature of such a gas is given by T = 2U/3R, where R is the universal gas constant. Mathematics A physical property of matter that quantitatively measures hotness, usually on the Celsius or Kelvin scales. It is a scalar quantity whose gradient determines heat flux (see Fourier’s law), and the heat in a given body will be in proportion to its temperature. See also heat equation, Newton’s law of cooling. Astronomy A measurement of the heat energy possessed by a body. Temperature can be measured in various ways, such as the total energy emitted (effective temperature), its emission at a single frequency (colour temperature), the mean velocity of the particles (kinetic temperature), the levels of excitation of electrons in atoms (excitation temperature), or degree of ionization (ionization temperature). In thermal equilibrium all measures of temperature will give the same value, but under other conditions they may give quite different temperatures. The kelvin scale is used for scientific measurements of temperature. Chemistry The property of a body or region of space that determines whether or not there will be a net flow of heat into it or out of it from a neighbouring body or region and in which direction (if any) the heat will flow. If there is no heat flow the bodies or regions are said to be in thermodynamic equilibrium and at the same temperature. If there is a flow of heat, the direction of the flow is from the body or region of higher temperature. Broadly, there are two methods of quantifying this property. The empirical method is to take two or more reproducible temperature-dependent events and assign fixed points on a scale of values to these events. For example, the Celsius temperature scale uses the freezing point and boiling point of water as the two fixed points, assigns the values 0 and 100 to them, respectively, and divides the scale between them into 100 degrees. This method is serviceable for many practical purposes (see temperature scales), but lacking a theoretical basis it is awkward to use in many scientific contexts. In the 19th century, Lord Kelvin proposed a thermodynamic method to specify temperature, based on the measurement of the quantity of heat flowing between bodies at different temperatures. This concept relies on an absolute scale of temperature with an absolute zero of temperature, at which no body can give up heat. He also used Sadi Carnot’s concept of an ideal frictionless perfectly efficient heat engine (see Carnot cycle). This Carnot engine takes in a quantity of heat q₁ at a temperature T, and exhausts heat q₂ at T₂, so that T₁/T₂ = q₁/q₂. If T₂ has a value fixed by definition, a Carnot engine can be run between this fixed temperature and any unknown temperature T₁, enabling T₁ to be calculated by measuring the values of q₁ and q₂. This concept remains the basis for defining thermodynamic temperature, quite independently of the nature of the working substance. The unit in which thermodynamic temperature is expressed is the kelvin. In practice thermodynamic temperatures cannot be measured directly; they are usually inferred from measurements with a gas thermometer containing a nearly ideal gas. This is possible because another aspect of thermodynamic temperature is its relationship to the internal energy of a given amount of substance. This can be shown most simply in the case of an ideal monatomic gas, in which the internal energy per mole (U) is equal to the total kinetic energy of translation of the atoms in one mole of the gas (a monatomic gas has no rotational or vibrational energy). According to kinetic theory, the thermodynamic temperature of such a gas is given by T = 2U/3R, where R is the universal gas constant. Chemical Engineering A measure of the intensity of heat that will flow into or out of a body or medium from another body or medium, and in which direction the heat flows. As a physical property of a body, it is proportional to the kinetic energy of the atoms or molecules. Where there is no heat flow, the body or medium is in thermodynamic equilibrium and at the same temperature as the other body or medium. Where they are not in equilibrium, the heat flows in the direction of the higher to the lower temperature body. There are various temperature scales used to quantify the property of temperature including kelvin, centigrade or Celsius, and Fahrenheit scales.
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