Physics
Temperature
Temperature is a measure of the average kinetic energy of the particles in a substance. It determines the direction of heat transfer between two objects and is commonly measured using the Celsius, Fahrenheit, or Kelvin scales. In physics, temperature plays a crucial role in understanding the behavior of matter and the transfer of thermal energy.
Written by Perlego with AI-assistance
Related key terms
1 of 5
10 Key excerpts on "Temperature"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
When two systems are at the same Temperature, no heat transfer occurs between them. When a Temperature difference does exist, heat will transfer from the warmer system to the colder system, until they are at thermal equilibrium. This transfer occurs via heat conduction. Statistically, Temperature ( T ) is a direct measure of the mean kinetic energy of the particles forming a sample of matter. For each degree of freedom that a particle possesses, the mean kinetic energy ( E k ) of the particles is: , where k is the Boltzmann constant, a fixed proportionality factor introduced by the system of units used to measure energy and Temperature. Macroscopically, Temperature is related to the amount of internal energy and enthalpy of a system: the higher the Temperature of a system, the higher its internal energy and enthalpy. For a system in thermal equilibrium at a constant volume, Temperature is thermodynamically defined in terms of its energy ( E ) and entropy ( S ) as: Temperature is an intensive property of a system, meaning that it does not depend on the system size, the amount or type of material in the system, the same as for the pressure ________________________ WORLD TECHNOLOGIES ________________________ and density. By contrast, mass, volume, and entropy are extensive properties, and depend on the amount of material in the system. Heat capacity When a sample is heated, meaning it receives thermal energy from an external source, some of the introduced heat is converted into kinetic energy, the rest to other forms of internal energy, specific to the material. The amount converted into kinetic energy causes the Temperature of the material to rise. The introduced heat ( Δ Q ) divided by the observed Temperature change is the heat capacity ( C ) of the material. If heat capacity is measured for a well defined amount of substance, the specific heat is the measure of the heat required to increase the Temperature of such a unit quantity by one unit of Temperature.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
When two systems are at the same Temperature, no heat transfer occurs between them. When a Temperature difference does exist, heat will transfer from the warmer system to the colder system, until they are at thermal equilibrium. This transfer occurs via heat conduction. Statistically, Temperature ( T ) is a direct measure of the mean kinetic energy of the particles forming a sample of matter. For each degree of freedom that a particle possesses, the mean kinetic energy ( E k ) of the particles is: , where k is the Boltzmann constant, a fixed proportionality factor introduced by the system of units used to measure energy and Temperature. Macroscopically, Temperature is related to the amount of internal energy and enthalpy of a system: the higher the Temperature of a system, the higher its internal energy and enthalpy. For a system in thermal equilibrium at a constant volume, Temperature is thermodynamically defined in terms of its energy ( E ) and entropy ( S ) as: Temperature is an intensive property of a system, meaning that it does not depend on the system size, the amount or type of material in the system, the same as for the pressure and density. By contrast, mass, volume, and entropy are extensive properties, and depend on the amount of material in the system. ________________________ WORLD TECHNOLOGIES ________________________ Heat capacity When a sample is heated, meaning it receives thermal energy from an external source, some of the introduced heat is converted into kinetic energy, the rest to other forms of internal energy, specific to the material. The amount converted into kinetic energy causes the Temperature of the material to rise. The introduced heat ( Δ Q ) divided by the observed Temperature change is the heat capacity ( C ) of the material. If heat capacity is measured for a well defined amount of substance, the specific heat is the measure of the heat required to increase the Temperature of such a unit quantity by one unit of Temperature.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
As a system receives heat, its Temperature rises; similarly, a loss of heat from the system decreases its Temperature. When two systems are at the same Temperature, no heat transfer occurs between them. When a Temperature difference does exist, heat will transfer from the warmer system to the colder system, until they are at thermal equilibrium. This transfer occurs via heat conduction. Statistically, Temperature ( T ) is a direct measure of the mean kinetic energy of the particles forming a sample of matter. For each degree of freedom that a particle possesses, the mean kinetic energy ( E k ) of the particles is: , where k is the Boltzmann constant, a fixed proportionality factor introduced by the system of units used to measure energy and Temperature. Macroscopically, Temperature is related to the amount of internal energy and enthalpy of a system: the higher the Temperature of a system, the higher its internal energy and enthalpy. For a system in thermal equilibrium at a constant volume, Temperature is thermodynamically defined in terms of its energy ( E ) and entropy ( S ) as: ____________________ WORLD TECHNOLOGIES ____________________ Temperature is an intensive property of a system, meaning that it does not depend on the system size, the amount or type of material in the system, the same as for the pressure and density. By contrast, mass, volume, and entropy are extensive properties, and depend on the amount of material in the system. Heat capacity When a sample is heated, meaning it receives thermal energy from an external source, some of the introduced heat is converted into kinetic energy, the rest to other forms of internal energy, specific to the material. The amount converted into kinetic energy causes the Temperature of the material to rise. The introduced heat ( Δ Q ) divided by the observed Temperature change is the heat capacity ( C ) of the material.
eBook - PDF- William Moebs, Samuel J. Ling, Jeff Sanny(Authors)
- 2016(Publication Date)
- Openstax(Publisher)
Chapter 1 | Temperature and Heat 7 1.1 | Temperature and Thermal Equilibrium Learning Objectives By the end of this section, you will be able to: • Define Temperature and describe it qualitatively • Explain thermal equilibrium • Explain the zeroth law of thermodynamics Heat is familiar to all of us. We can feel heat entering our bodies from the summer Sun or from hot coffee or tea after a winter stroll. We can also feel heat leaving our bodies as we feel the chill of night or the cooling effect of sweat after exercise. What is heat? How do we define it and how is it related to Temperature? What are the effects of heat and how does it flow from place to place? We will find that, in spite of the richness of the phenomena, a small set of underlying physical principles unites these subjects and ties them to other fields. We start by examining Temperature and how to define and measure it. Temperature The concept of Temperature has evolved from the common concepts of hot and cold. The scientific definition of Temperature explains more than our senses of hot and cold. As you may have already learned, many physical quantities are defined solely in terms of how they are observed or measured, that is, they are defined operationally. Temperature is operationally defined as the quantity of what we measure with a thermometer. As we will see in detail in a later chapter on the kinetic theory of gases, Temperature is proportional to the average kinetic energy of translation, a fact that provides a more physical definition. Differences in Temperature maintain the transfer of heat, or heat transfer, throughout the universe. Heat transfer is the movement of energy from one place or material to another as a result of a difference in Temperature. (You will learn more about heat transfer later in this chapter.) Thermal Equilibrium An important concept related to Temperature is thermal equilibrium.
eBook - PDF- James Shipman, Jerry Wilson, Charles Higgins, Bo Lou, James Shipman(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
This answer is not exactly 688F, but it is close enough to give you an idea of the Fahrenheit tem- perature. (Remember this simple conversion on your next trip abroad.) Conceptual Question and Answer 5.1 Did You Learn? ● ● Temperature is a measure of the average kinetic energy of the molecules of a substance. ● ● There is no known upper limit to Temperature, and the lower limit is absolute zero (0 K, 22738C, or 24608F). 5.2 Heat Key Questions ● ● Why is heat called “energy in transit”? ● ● Most substances contract with decreasing Temperature. Is this true for water? Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 112 Chapter 5 ● Temperature and Heat We commonly describe heat as a form of energy. However, this definition can be made more descriptive. The molecules of a substance may vibrate back and forth, rotate, or move from place to place. They have kinetic energy. As stated previously, the average kinetic energy of the molecules of a substance is related to its tempera- ture. For example, if an object has a high Temperature, the average kinetic energy of the molecules is relatively high. (The molecules move relatively faster.) In kinetic theory of gases (section 5.6), the kinetic energy is actually the average translational kinetic energy of the molecules. (Translation means that the molecule moves lin- early as a whole.) For a diatomic gas, however, besides having this translational “Temperature” kinetic energy, the molecules may also have kinetic energy due to vibrations and rotations.
eBook - PDF- T. J. Quinn(Author)
- 2013(Publication Date)
- Academic Press(Publisher)
Closely linked to the concept of Temperature, and often confused with it, is the concept of heat. While it is a matter of common experience that some substances require more heat to warm them than do others, it is not immediately obvious why this should be so. Nevertheless, given sufficient insight, common experience allows us to make a number of very fundamen-tal statements about the thermal behaviour of matter: these statements comprise the laws of thermodynamics. The zeroth law, so-called because it came to be formulated after the first and second laws, is concerned with the state of bodies brought into thermal contact with one another. In order to understand clearly what this means, we must first of all define a few terms. The following definitions, although not rigorously exact, allow us to make a few general statements about the meaning of Temperature and the thermal behaviour of matter that are useful in introducing the subject of thermo-metry. The reader is referred to the texts on thermodynamics and statistical mechanics cited in the bibliography to this chapter for a more detailed discussion of the fundamentals of thermal physics. We shall often find ourselves talking about a system, by which we mean a macroscopic entity extending in space and time and accessible to normal processes of measurement. Such a system is considered to consist of a very large number of material particles or field quantities such as photons, or both. In all cases they are dynamical systems having an extremely large 7 The Meaning of Temperature 3 number of degrees of freedom. An isolated system is one which has no interaction whatever with its surroundings, while a closed system is one which has no material exchange with its surroundings. If an isolated system is left standing, it eventually reaches a configuration or state from which it does not subsequently depart. This final state is called the thermal equilib-rium state of the system.
eBook - PDFRealTime Physics: Active Learning Laboratories, Module 2
Heat and Thermodynamics
- David R. Sokoloff, Priscilla W. Laws, Ronald K. Thornton(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
While we will use some of the concepts from mechanics—such as work and kinetic energy—in our discussion of thermodynamics, we will also introduce some new terms. Although you have already encountered some of these terms, 4 REALTIME PHYSICS: HEAT AND THERMODYNAMICS such as heat and Temperature in everyday situations, we will need to define them more precisely. Other new terms such as adiabatic and isothermal, which will be introduced in future labs, are probably less familiar but also very useful. Temperature is one of the most familiar and fundamental thermodynamic quantities, and it is the major focus of study in this first lab. In the first investi- gation of this lab, you will look at how Temperature can be measured using a glass bulb thermometer and using an electronic Temperature sensor interfaced with a microcomputer. You will use these to explore the Celsius and Kelvin Temperature scales. In later activities you will take a much more careful look at the concept of Temperature. In particular, you will observe how the Temperature of a substance or system is affected when it interacts with its surroundings or another substance at a different Temperature. Whenever the Temperature of something changes, we say glibly that it has undergone a thermal interaction. When the Temperature of a system remains constant, we refer to it as being in thermal equilibrium. Since we cannot see what really goes on when something changes Temperature, we have to develop some new concepts to try to explain what is happening. One of these new concepts is that of heat transfer. It is essential to understand the difference be- tween the Temperature of an object and the heat transferred to or from the object. This will be a major focus of this lab. INVESTIGATION 1: Temperature MEASUREMENT Temperature is a familiar concept to all of us. Thermometers register changes in Temperature by using materials that change in some way as they are heated or cooled.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter-9 Thermodynamic Temperature Thermodynamic Temperature is the absolute measure of Temperature and is one of the principal parameters of thermodynamics. Thermodynamic Temperature is an absolute scale because it is the measure of the fundamental property underlying Temperature: its null or zero point, absolute zero, is the Temperature at which the particle constituents of matter have minimal motion and can become no colder. Overview Temperature arises from the random submicroscopic vibrations of the particle consti-tuents of matter. These motions comprise the kinetic energy in a substance. More specifi-cally, the thermodynamic Temperature of any bulk quantity of matter is the measure of the average kinetic energy of a certain kind of vibrational motion of its constituent particles called translational motions. Translational motions are ordinary, whole-body movements in three-dimensional space whereby particles move about and exchange energy in collisions. Figure 1 below shows translational motion in gases; Figure 4 below shows translational motion in solids. Thermodynamic Temperature's null point, absolute zero, is the Temperature at which the particle constituents of matter are as close as possible to complete rest; that is, they have minimal motion, retaining only quantum mechanical motion. Zero kinetic energy remains in a substance at absolute zero. Throughout the scientific world where measurements are made in SI units, thermody-namic Temperature is measured in kelvins (symbol: K). Many engineering fields in the U.S. however, measure thermodynamic Temperature using the Rankine scale. By international agreement, the unit kelvin and its scale are defined by two points: absolute zero, and the triple point of Vienna Standard Mean Ocean Water (water with a specified blend of hydrogen and oxygen isotopes).
- Christof M. Aegerter(Author)
- 2018(Publication Date)
- Cambridge University Press(Publisher)
This definition of the Temperature naturally gives an absolute zero, namely where all particles have the same kinetic energy (zero). At the top of the scale, there are no limits to the Temperature. For instance, inside the sun the Temperature can be about 15 million degrees. 8.2 Temperature and the Ideal Gas Let us now look at a quantitative, microscopic interpretation of Temperature and other thermodynamic variables. To this end, we investigate the model system of the ideal gas, in which this approach can be well illustrated. An ideal gas can be seen as a collection of small spheres, all of which are colliding completely elastically with each other and are so small that they only meet when they are directly flying toward each other. The results will then be generalized to other states that are related to thermal motion. Let us first look briefly at which parameters can characterize an (ideal) gas and how these are connected before we derive a microscopic interpretation. 8.2.1 Ideal Gases The macroscopic parameters necessary to describe the equilibrium state of a gas quantity are pressure, volume, and Temperature. Temperature we still understand as the property indicated by a thermometer, which is in thermal contact with our gas. For the pressure exerted by the gas on the walls of a vessel, we think of the force per unit of area (as discussed in hydrostatics) measured in the following: Pascal = Newton m 2 A gas is considered ideal if one can neglect the interaction between the individual molecules, which is appropriate when the distances between the individual molecules are sufficiently large on average that they do not notice their mutual attraction and the reciprocal repulsion. Very small distances for a short time make an elastic impact possible. For ideal gases, there is a relationship between the pressure p, the volume of a mole (containing N 0 = 6.023 × 10 23 atoms) V, and the absolute Temperature T (in Kelvin), the state equation.
eBook - PDF- Richard Dodd(Author)
- 2011(Publication Date)
- Cambridge University Press(Publisher)
9 Unit of thermodynamic Temperature (kelvin) 9.1 SI definition of the kelvin The kelvin, unit of thermodynamic Temperature, is the fraction 1/273.16 of the thermodynamic Temperature of the triple point of water. The dimension of thermodynamic Temperature is [], its unit is the kelvin and its symbol is K. 9.1.1 Possible future definition of the kelvin Under discussion at the present time is the redefining of the unit of Temperature in the following way: The kelvin is a unit of thermodynamic Temperature such that the Boltzmann constant is exactly 1.380 650 5 × 10 −23 J . K −1 (joules per kelvin). 9.1.2 Definition of Temperature The average kinetic energy of the molecules, atoms and ions that comprise an object may be used as a measure of its thermodynamic Temperature. Given two objects with different Temperatures, the one with the higher temper- ature (the hotter object) will transfer heat to the object with the lower Temperature (the cooler object) by means of radiation, convection or conduction, depending on the nature of the objects and their location, until the Temperatures of the objects are equalized. 9.1.3 Thermodynamic Temperature The thermodynamic Temperature, T t , of a system may be defined as the inverse of the rate of change of entropy S , with respect to the internal energy U , assuming that the volume V of the system and the number of its constituent parts N remain 146 9.2 Temperature scales 147 constant, 54 i.e. T t = ∂S ∂U −1 N,V (9.1) The entropy S , is a measure of the disorder of the system and increases with increasing levels of disorder (e.g., steam has a higher entropy than water, which in turn has a higher entropy than ice).
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
