Potential energy, neglection

The unsteady-state balance equation for this system (air within the engine housing) is the first law of thermodynamics for open systems with changes in kinetic and potential energies neglected. Also, the temperature and composition of the system contents are assumed independent of position and no phase changes occur. This gives the equation... 

If the vihriilioiis arc sin all (c.g.. low Lcinpcralurcs. rigiti bontliiig framework), the higher order terms can be neglected. Thus the potential energy simplifies to... 

Calculation of Ideal Work If changes in kinetic and potential energies are neglected, Eq. (4-360) is apphcable. From the tabulated data,... 

Neglecting changes in kinetic energy and potential energy produces ... 

Consider the thermodynamic process in the fan (Fig. 9.33). As the fan is a stationary flow system, consideration is directed to the total enthalpy change. As the suction openings are often at the same, or almost the same level, the potential energy change can be neglected. 

Figure S-1. Form of a potential energy curve for diatomic molecule AB. VfrAa) is the potential energy, Tab is the intemuclear distance, is the equilibrium intemuclear distance, and D is the bond dissociation energy. (The zero point energy is neglected in the figure.)...

The package has a mass of 2 kg or a weight of 4.415 lb. Assume a downward velocity of about 10 ft/s. The shock absorber develops a constant force (independent of the relative velocity) of 10 lb (44.48 N). The spring stiffness is 57.10 Ib/in. The potential energy due to gravity will be neglected. 

Wigner s formula is open to criticism also on another point, since he assumes the existence of a stationary electron state where the density is so low that the kinetic energy may be neglected. This is in contradiction to the virial theorem (Eq. 11.15), which tells us that the kinetic energy can never be neglected in comparison to the potential energy and that the latter quantity is compensated by the former to fifty per cent. A reexamination of the low density case would hence definitely be a problem of essential interest. 

The Hamiltonian for this system should include the kinetic and potential energy of the electron and both of the nuclei. However, since the electron mass is more than a thousand times smaller than that of the lightest nucleus, one can consider the nuclei to be effectively motionless relative to the quickly moving electron. This assumption, which is basically the Born-Oppenheimer approximation, allows one to write the Schroedinger equation neglecting the nuclear kinetic energy. For the Hj ion the Born-Oppenheimer Hamiltonian is... 

Here, AS° = AS i + AS n, but since identical vibrational levels have been assumed for the two electronic levels, AS jb = 0. In addition, AS j is related to the electronic degeneracies of the two levels by ASei = K In ( l/ h)- Finally, if the transformation takes place at constant pressure, AH° = NAE where AE is defined as above. Consideration of the Gibbs free energy for an assembly of N molecules thus produces the same relation for the HS fraction Uh as the potential energy for the isolated molecule, if only the interaction between the molecules is neglected. 

In chemical processes, the kinetic and potential energy terms are usually small compared with the heat and work terms, and can normally be neglected. 

The kinetic and potential energy of the process streams will be small and can be neglected. Take the first system boundary to include the reboiler and condenser. 

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