Part II First Law of Thermodynamics
... with increasing x. Therefore, a negative sign is added in Eq. 2-8 to make heat transfer in the positive x direction a positive quantity. Note: Temperature is a measure of the kinetic energies of the molecules. In a liquid or gas, the kinetic energy of the molecules is due to the random motion of the ...
... with increasing x. Therefore, a negative sign is added in Eq. 2-8 to make heat transfer in the positive x direction a positive quantity. Note: Temperature is a measure of the kinetic energies of the molecules. In a liquid or gas, the kinetic energy of the molecules is due to the random motion of the ...
Document
... Example 19-10: First law in isobaric and isovolumetric processes. An ideal gas is slowly compressed at a constant pressure of 2.0 atm from 10.0 L to 2.0 L. (In this process, some heat flows out of the gas and the temperature drops.) Heat is then added to the gas, holding the volume constant, and the ...
... Example 19-10: First law in isobaric and isovolumetric processes. An ideal gas is slowly compressed at a constant pressure of 2.0 atm from 10.0 L to 2.0 L. (In this process, some heat flows out of the gas and the temperature drops.) Heat is then added to the gas, holding the volume constant, and the ...
Thermo applications
... thermodynamic functions of interest, namely enthalpy, entropy, and Gibbs free energy, are all state functions, their values can be calculated independently of any reaction path. In general, the partial molal enthalpy of any chemical species is a function of temperature, pressure, and composition. Th ...
... thermodynamic functions of interest, namely enthalpy, entropy, and Gibbs free energy, are all state functions, their values can be calculated independently of any reaction path. In general, the partial molal enthalpy of any chemical species is a function of temperature, pressure, and composition. Th ...
Thermal conductivity of individual silicon nanowires
... reduced. This clearly indicates that enhanced boundary scattering has a strong effect on phonon transport in Si nanowires. 共ii兲 For the 37, 56, and 115 nm diam wires, thermal conductivities reach their peak values around 210, 160, and 130 K, respectively. This is in sharp contrast to the peak of bul ...
... reduced. This clearly indicates that enhanced boundary scattering has a strong effect on phonon transport in Si nanowires. 共ii兲 For the 37, 56, and 115 nm diam wires, thermal conductivities reach their peak values around 210, 160, and 130 K, respectively. This is in sharp contrast to the peak of bul ...
chemical equilibrium
... greater average energy + more frequent collisions more frequent collisions for gaseous molecules lower activation energy ...
... greater average energy + more frequent collisions more frequent collisions for gaseous molecules lower activation energy ...
State of Equilibrium
... equilibrium, which might be more correctly named thermostatics. The measurement of thermodynamic properties relies on the measuring device being in equilibrium with the system. For example, a thermometer must be in thermal equilibrium with a system if it is to measure its temperature, which explains ...
... equilibrium, which might be more correctly named thermostatics. The measurement of thermodynamic properties relies on the measuring device being in equilibrium with the system. For example, a thermometer must be in thermal equilibrium with a system if it is to measure its temperature, which explains ...
2. THERMODYNAMICS and ENSEMBLES (Part A) Introduction
... statement as to which face is uppermost for each one of them. ...
... statement as to which face is uppermost for each one of them. ...
Jeopardy Heat
... their feet burned. How might this be possible? The ashes are poor conductors of heat. H = kAT/L where k = thermal conductivity coefficient in Watts/(m*K) ...
... their feet burned. How might this be possible? The ashes are poor conductors of heat. H = kAT/L where k = thermal conductivity coefficient in Watts/(m*K) ...
Black body
A black body (also blackbody) is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A white body is one with a ""rough surface [that] reflects all incident rays completely and uniformly in all directions.""A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic radiation called black-body radiation. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone (see figure at right), not by the body's shape or composition.A black body in thermal equilibrium has two notable properties:It is an ideal emitter: at every frequency, it emits as much energy as – or more energy than – any other body at the same temperature.It is a diffuse emitter: the energy is radiated isotropically, independent of direction.An approximate realization of a black surface is a hole in the wall of a large enclosure (see below). Any light entering the hole is reflected indefinitely or absorbed inside and is unlikely to re-emerge, making the hole a nearly perfect absorber. The radiation confined in such an enclosure may or may not be in thermal equilibrium, depending upon the nature of the walls and the other contents of the enclosure.Real materials emit energy at a fraction—called the emissivity—of black-body energy levels. By definition, a black body in thermal equilibrium has an emissivity of ε = 1.0. A source with lower emissivity independent of frequency often is referred to as a gray body.Construction of black bodies with emissivity as close to one as possible remains a topic of current interest.In astronomy, the radiation from stars and planets is sometimes characterized in terms of an effective temperature, the temperature of a black body that would emit the same total flux of electromagnetic energy.