This glossary of engineering terms is a list of definitions about the major concepts of engineering. Please see the bottom of the page for glossaries of specific fields of engineering.
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where is the infinitesimal amount of heat absorbed by the system from the reservoir and is the temperature of the external reservoir (surroundings) at a particular instant in time. In the special case of a reversible process, the equality holds. [114] The reversible case is used to introduce the entropy state function. This is because in a cyclic process the variation of a state function is zero. In words, the Clausius statement states that it is impossible to construct a device whose sole effect is the transfer of heat from a cool reservoir to a hot reservoir. [115] Equivalently, heat spontaneously flows from a hot body to a cooler one, not the other way around. [116] The generalized "inequality of Clausius" [117]
Thus, it is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt:
The coulomb is equivalent to the charge of approximately 6.242×1018 (1.036×10−5 mol) protons, and −1 C is equivalent to the charge of approximately 6.242×1018 electrons.
A new definition, in terms of the elementary charge, will take effect on 20 May 2019. [141]
The new definition defines the elementary charge (the charge of the proton) as exactly 1.602176634×10−19 coulombs. This would implicitly define the coulomb as 1⁄0.1602176634×1018 elementary charges.where ke is the Coulomb constant (ke ≈ 9×109 N⋅m2⋅C−2), q1 and q2 are the signed magnitudes of the charges, and the scalar r is the distance between the charges. The force of the interaction between the charges is attractive if the charges have opposite signs (i.e., F is negative) and repulsive if like-signed (i.e., F is positive).
Being an inverse-square law, the law is analogous to Isaac Newton's inverse-square law of universal gravitation. Coulomb's law can be used to derive Gauss's law, and vice versa.The first case can be a result of tensile (pulling) forces, compressive (pushing) forces, shear, bending, or torsion (twisting).
In the second case, the most significant factor, which is determined by the temperature, is the mobility of the structural defects such as grain boundaries, point vacancies, line and screw dislocations, stacking faults and twins in both crystalline and non-crystalline solids. The movement or displacement of such mobile defects is thermally activated, and thus limited by the rate of atomic diffusion. [152] [153]The internal moment M(x) is the integral of the internal shear:
The angle of rotation from the horizontal, , is the integral of the internal moment divided by the product of the Young's modulus and the area moment of inertia:
Integrating the angle of rotation obtains the vertical displacement :
This constant has a simple relation to two other physical constants:
where
where:
where and are the masses of the two particles, is the distance between them, and is the gravitational constant. [255]
Close to the Earth's surface, the gravitational field is approximately constant, and the gravitational potential energy of an object reduces to
where , and are the pressure, volume and temperature; is the amount of substance; and is the ideal gas constant. It is the same for all gases.
It can also be derived from the microscopic kinetic theory, as was achieved (apparently independently) by August Krönig in 1856 [278] and Rudolf Clausius in 1857. [279]When any system at equilibrium for a long period of time is subjected to a change in concentration, temperature, volume, or pressure, (1) the system changes to a new equilibrium, and (2) this change partly counteracts the applied change.
It is common to treat the principle as a more general observation of systems, [309] such as
When a settled system is disturbed, it will adjust to diminish the change that has been made to it
or, "roughly stated", [309]
Any change in status quo prompts an opposing reaction in the responding system.
For example, log2 64=6, as 26=64.
The logarithm base 10 (that is b=10) is called the decimal or common logarithm and is commonly used in science and engineering. The natural logarithm has the number e (that is b ≈ 2.718) as its base; its use is widespread in mathematics and physics, because of its simpler integral and derivative. The binary logarithm uses base 2 (that is b=2) and is frequently used in computer science. Logarithms are examples of concave functions.... boson: A force-carrying particle, as opposed to a matter particle (fermion). Bosons can be piled on top of each other without limit. Examples include photons, gluons, gravitons, weak bosons, and the Higgs boson. The spin of a boson is always an integer, such as 0, 1, 2, and so on ...
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Computer System engineering has traditionally been viewed as a combination of both electronic engineering (EE) and computer science (CS).
A "field" is any physical quantity which takes on different values at different points in space.
a person or thing that imparts motion, esp. a contrivance, as a steam engine, that receives and modifies energy from some source in order to utilize it in driving machinery.
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The human eye has the ability to respond to all the wavelengths of light from 400–700 nm. This is called the visible part of the spectrum.
Light is a special class of radiant energy embracing wavelengths between 400 and 700 nm (or mμ), or 4000 to 7000 Å.