Mechanical work performed

The area contained within the P-V diagram represents the total mechanical work performed by the piston. Some of this work is required to sustain the cycle and must be subtracted from the work calculated tiom the P-V diagram to determine the total external work available from ilie piston. 

Chapter 16 applies thermodynamics to problems of biological interest. The metabolic processes leading to mechanical work performed by a living organism are described first, followed by discussions of the role of thermodynamics as a tool for understanding the stabilities of biopolymers such as proteins, and oligonucleotides as model compounds for DNA. 

These thermodynamic concepts denote the energy which is bound during the formation of a given compound from its constituent elements at constant volume (energy of formation) or at constant pressure (enthalpy of formation, which includes the mechanical work performed at the standard state44) (25 °C = 77°F and a pressure of 1 bar). The data are tabulated in accordance with thermodynamic convention if the formation of a compound from its elements is... 

The third concept to consider is how energy can flow between bodies. It can happen by only two mechanisms by mechanical work performed on the body and by heating. Heating is energy" flow driven by a temperature difference between two bodies. 

The Cu-Cu bond is 177 kJ/mole. Assuming a pressure of 15 kPa, a velocity of 130 cm/sec, and a polish rate of 500 nm/min, compare the mechanical work performed by the pad/slurry system to the copper bond energy. The work... 

We begin with the general formulation for the energy change of a system by noting the corresponding expression for the surroundings, as indicated by the subscript zero. Here we replace the heat transferred into the bath by drQo = Tod So, and the mechanical work performed, by drW = —PdVo, so that... 

In equation (6-1) the increment of work, dW, refers to all of the work (i.e., electrical, mechanical, pressure-volume, chemical, etc.) performed by the system (the sample) on its surroundings. The development of thermodynamics given in most physical chemistry texts is confined to gases where d W becomes simply pressure-volume work, PdV, where P is the external environment. In the case of an elastomer deformed by an amount dL in tension and exerting a restoring force f the mechanical work performed on the system to accomplish the deformation, namely fdL, must also be included in dW. Thus, for an elastomer strained uni axially in tension,... 

When one talks about reversibility of the Rehbinder effect, the presence of a thermodynamically stable interface between mutually saturated solid phase and the liquid, as well as complete disappearance of these effects upon the removal of the medium (e.g. by evaporation) are implied. These features emphasize principal difference between the Rehbinder effect and corrosive action of the medium. At the same time, one has to realize that it is not possible to draw here a distinct border line. The term disintegration covers a broad range of processes from idealized cases of purely mechanical breaking to destruction by corrosion or dissolution. The Rehbinder effect, i.e. the lowering of strength due to adsorption and chemisorption, stress-caused corrosion, and corrosion fatigue, occupies some intermediate place between these extremes. All these phenomena represent a certain degree of combination between the mechanical work performed by external forces and chemical (physico-chemical) interaction with the medium. 

You may recognize (pressure) (volume) as the mechanical work performed in a system where pressure and volume can change. By the convention stated above, the work is negative if it is done by the system. Thus, Equation 2.5.1 becomes... 

If we knew the heat of the transition for the elastic band under load, /SH, we could calculate the ratio of the mechanical work performed to the heat input expended in lifting the load. 

The energy liberated during explosive processes can be used for performing mechanical work. The sum of all forms of mechanical work performed is assigned as the total work done on account of the energy of an expletive. 

The mechanical work performed by engine when a point of fiber loop performs o complete rotation is given by the following expression ... 

The mechanical work performed per unit mass of collagen transferred W ... 

In the above equation dQ denotes the amount of heat entering the system (the symbol d represents an inexact differential), —PdV is the amount of mechanical work performed on the system (P is the hydrostatic pressure and V is the system volume), and fidN is the so-called chemical work performed on the system (/u., and Ni are respectively the chemical potential and the molecular count of the ith chemical species). 

In defining escaping tendency [11], Lewis and Randall use classical mechanics as an analogy, where the mechanical work performed is regarded as the product of a capacity and a potential . This model is the basis for each term in Eq. (2). Therefore, in the last term of Eq. (2), the ehemical potential, p -, can be seen as flic potential with the eapacity unit represented by either the partial pressure, x or the mole fraction, Xy ... 

Energy sinks occur in the form of heat loss, mechanical work performed and biological production . The latter term describes growth (increase in body size and - content) as well as the replacements of body parts lost during day-to-day live (hair, nail, skin and gut cells and enzymes lost). It also involves foetuses and maternal milk. To clarify the different energy sinks and not to mix possible different pathways of substrates at different metabolic situations the energy losses are usually divided into ... 

At compression along a line 2b 1, the work is taken over by external forces therefore the mechanical work performed by the gas is A2, l < 0. As the work performed by an ideal gas on the graph in coordinates p-V is, numerically equal to the area of a curvilinear trapeze, the difference between these areas, (the shaded area) is numerically equal to the work accomplished by the gas for a cycle. It is accepted that the cycle going clockwise is direct (Adc= f pdV>6) and the cycle is reversed if it goes in the opposite direction (Figure 3.17), i.e., Adc= pdV<0. 

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