Engineering Equations





Engineering Equations
NUMBER DESCRIPTION EQUATION DEPT
1 Ohm’s Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. $${\displaystyle V=IR}$$ ECEN
2 Bayes’ Theorem describes the probability of an event, based on prior knowledge of conditions that might be related to the event. $${\displaystyle P(A\mid B)=\frac {P(B\mid A)P(A)}{P(B)}}$$ ISEN
3 The evolution of a Linear Dynamical System subject to inputs may be modeled with a first order matrix differential equation. This equation is ubiquitous in engineering. $${\displaystyle {\dot {x}}=AX+Bu}$$ ALL
4 Laplace’s equation is a second-order elliptic partial differential equation. The solutions of Laplace’s equation are important in many fields of engineering, notably electromagnetism, astronomy, and fluid dynamics, because they can be used to accurately describe the behavior of electric, gravitational, and fluid potentials. $${\displaystyle \nabla ^{2}\varphi = 0}$$ ALL
5 The Navier-Stokes Momentum Equations describe the motion of viscous fluid substances. These equations describe the physics of many phenomena of engineering and scientific interest. $${\displaystyle {\frac {\partial \mathrm{u}}{\partial t}} + \mathrm{u} \cdot \nabla \mathrm{u} = – {\frac {\nabla P}{\rho} + \nu \nabla^{2} \mathrm{u}}}$$ AERO, CHEN, MEEN
6 The Cauchy Momentum Equation is a vector partial differential equation that describes the non-relativistic momentum transport in any continuum. Essentially, the time derivative of the flow vector field is related to the divergence of the stress tensor and to the body forces per unit mass. $${\displaystyle {\frac {D{\mathrm {u}}}{Dt}}={\frac 1\rho }\nabla \cdot {\sigma }+{\mathrm {g}}}$$ ALL
7 The Reynolds Number is an important dimensionless quantity in fluid mechanics that is used predict flow patterns in different fluid flow situations. It is the ratio of inertial forces to viscous forces. $${\displaystyle \mathrm {Re} ={\frac {\mu L}{\nu }}}$$ AERO, CHEN, MEEN
8 The Ideal Gas Law is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of gases under many conditions. $${\displaystyle PV=nRT}$$ AERO, CHEN, MEEN, PETE
9 Newton’s Second Law of Motion states that the vector sum of forces on an object equals the mass of the object multiplied by its acceleration for an inertial observer. $${\displaystyle F = ma}$$ ALL
10 The Lagrange Equations are a convenient form to model the motion of systems. They may be viewed as a different form of Newton’s second laws. The Lagrange equations are ideal for systems with conservative forces and for bypassing constraint forces in any coordinate system. $${\displaystyle \frac {d}{dt}\left(\frac {\partial L}{\partial \dot {q}_n}\right)-\frac{\partial L}{\partial q_n}=0}$$ AERO, MEEN
11 Kepler’s Equation is a transcendental equation that relates the Mean anomaly of orbital motion to the Ecentric anomaly and orbit eccentricity for a body subject to a central force. $${\displaystyle M = E – e \sin E}$$ AERO
12 Newton’s Universal Law of Gravitation states that a particle attracts other particles in the universe through a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This is a general physical law derived from empirical observations. $${\displaystyle F=G{\frac {m_{1}m_{2}}{r^{2}}}}$$ AERO
13 Fick’s Second Law of Diffusion is a partial differential equation that predicts how diffusion causes a concentration to change with time. It is essentially the Heat Equation. $${\displaystyle {\frac {\partial \varphi }{\partial t}}=D{\frac {\partial ^{2}\varphi }{\partial x^{2}}}}$$ AERO, CVEN
14 The Convection- Diffusion-Reaction Equation for Mass Transport is a combination of the diffusion and convection equations, and describes physical phenomena where particles, energy, or other physical quantities are transferred inside a physical system due to convection, diffusion and reactions. $${\displaystyle {\frac {\partial c}{\partial t}}=\mathrm {\nabla } \cdot (D\mathrm {\nabla } c)-\mathrm {\nabla } \cdot (\vec{v} c)+R}$$ AERO, CHEN
15 Diffusivity Equation for the flow of a single phase fluid in a porous media. $${\displaystyle c(\nabla p)^{2}+\nabla^{2}p = \frac {\phi \mu c_t}{k} \frac {\partial p}{\partial t}}$$ CHEN, PETE
16 The Wave Equation is a second-order linear hyperbolic partial differential equation for the description of waves as they occur in classical physics. The equation can be used to model sound waves, light waves, and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics $${\displaystyle {\frac {\partial ^{2}u}{\partial t^{2}}}=c^{2}\nabla ^{2}u}$$ ALL
17 Einstein’s Mass-Energy Equivalence states that anything having mass has an equivalent amount of energy and vice versa, with these fundamental quantities directly relating to one another by Einstein’s famous formula. The formula arose from special relativity. $${\displaystyle E=mc^{2}}$$ NUEN
18 The Fourier transform decomposes a signal into the frequencies that make it up, in a way similar to how a musical chord can be expressed as the frequencies (or pitches) of its constituent notes. $${\displaystyle g(t)=\int_{-\infty}^{\infty}G(f)e^{i2\pi ft}df}$$ ECEN
19 The Clausius Inequality is a fundamental statement of the Second Law of Thermodynamics. It recognizes that the cyclic integral of heat transfer Q between a system at temperature T and its surroundings is less than zero for all cases but the idealized case of reversibility. The inequality leads to the definition of the non-conserved property of entropy and the reality of entropy generation in real processes. $${\displaystyle \oint {\frac {\delta Q}{T_{surr}}}\leq 0}$$ MEEN, AERO
20 The Mechanical Equivalency of Heat states that the cyclic integral of heat transfer is equal to the cyclic integral of work transfer between a system and its surroundings. It was discovered by Joule In his famous experiments and created the basis upon which Conservation of Energy, and thus the First Law of Thermodynamics, were based. It leads to the definition of the property internal energy. $${\displaystyle \oint {\delta Q}=\oint {\delta W}}$$ ALL
21 The Boltzmann Entropy Equation shows the relationship between entropy and the number of ways the atoms or molecules of a thermodynamic system can be arranged. $${\displaystyle S = K \log W}$$ AERO, OCEN
22 Newton’s Law of Cooling states that the rate of heat loss of a body is directly proportional to the difference in the temperatures between the body and its surroundings, provided the temperature difference is small and the nature of radiating surface remains same. $${\displaystyle {\dot {Q}} = Ah {\Delta {T}}(t)}$$ ALL
23 The Fundamental Equation of Nanoindentation developed by Texas A&M’s own George Pharr. $${\displaystyle S = 2E_r {\frac {\sqrt {A}}{\sqrt {\pi}}}}$$ MSEN
24 The Planck Constant is a physical constant that is the quantum of action and is central in quantum mechanics. It is defined as the ratio of particulate photon energy and its associated wave frequency. $${\displaystyle h = \frac {E}{f}}$$ AERO
25 The Stefan-Boltzmann Law describes the power radiated from a black body in terms of its temperature. Specifically, the total energy radiated per unit surface area of a black body across all wavelengths per unit time is proportional to the fourth power of the black body’s thermodynamic temperature. $${\displaystyle j^{*} = \sigma T^{4}}$$ NUEN
26 Arps equation is a mathematical model to forecast future production rates of oil and gas wells. $${\displaystyle q = \frac {q_i}{(1+bD_it)^{\frac {1}{b}}}}$$ PETE
27 Archie’s Law relates the in-situ electrical conductivity of a sedimentary rock to its porosity and brine saturation. It is an empirical law attempting to describe ion flow in clean, consolidated sands, with varying intergranular porosity. $${\displaystyle C_t = \frac {1}{a}C_{w}\phi^{m}S_w^n}$$ CVEN, PETE
28 Darcy’s Law is an equation that describes the flow of a fluid through a porous medium. The law was formulated on the results of experiments involving the flow of water through beds of sand, and it forms the basis of hydrogeology. $${\displaystyle q = \frac {kA}{\mu} \frac {dp}{dL}}$$ CHEN, PETE
29 Bragg’s Law is a relationship describing the angles for coherent and incoherent scattering from a crystal lattice. Specifically, it describes the condition for maximum constructive interference. $${\displaystyle n\lambda = 2d \sin \theta}$$ AERO, BAEN, ECEN
30 Amdahl’s law is a formula that gives the theoretical speedup in latency of the execution of a task at fixed workload that can be expected of a system whose resources are improved. This law is commonly used in parallel computing to predict the theoretical speedup when using multiple processors. $${\displaystyle S_{latency}(s) = \frac {1}{(1-p)+\frac {p}{s}}}$$ CSCE
31 An M/M/1 Queue represents the queue length in a system having a single server, where arrivals are determined by a Poisson process and job service times have an exponential distribution. The model is the most elementary of queueing models. $${\displaystyle L_q = \left(\frac {\lambda}{\mu}\right)\left(\frac{\lambda}{\mu – \lambda}\right)}$$ ISEN
32 Linear programming is a method to achieve the best outcome in a mathematical model whose requirements are represented by linear relationships. $${\displaystyle \max\{c^{T}x | Ax \leq b \wedge x \geq 0 \}}$$ ISEN
33 Stirling’s approximation is an approximation for factorials. It is a good-quality approximation, leading to accurate results even for small values of n. It is commonly used in the analysis of algorithms. $${\displaystyle n! = \sqrt{2\pi n}\left(\frac{n}{e}\right)^{n}\left(1+O\left(\frac{1}{n}\right)\right)}$$ CSCE
34 Taylor Series is a representation of a function as an infinite sum of terms that are calculated from the values of the function’s derivatives at a single point. $${\displaystyle \sum _{n=0}^{\infty }{\frac {f^{(n)}(a)}{n!}}(x-a)^{n}}$$ MEEN
35 Hooke’s law is a principle of physics that states that the force (or stress) needed to extend or compress a spring (or continuum media) by some distance (or strain) scales linearly with respect to that distance. $${\displaystyle \sigma = – c\varepsilon}$$ MEEN
36 Gauss’s law relates the distribution of electric charge to the resulting electric field. This law can be expressed in an integral form or differential form: the differential form is shown here. $${\displaystyle \nabla \cdot E = \frac {\rho}{\varepsilon _0}}$$ ECEN, AERO
37 Gauss’s law for magnetism is one of the four Maxwell’s equations that underlie classical electrodynamics. It states that the magnetic field B has divergence equal to zero, in other words, that it is a solenoidal vector field $${\displaystyle \nabla \cdot B = 0}$$ ECEN, AERO
38 Faraday’s Law of Induction is a basic law of electromagnetism that predicts how a magnetic field will interact with an electric circuit to produce an electromotive force. It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids. $${\displaystyle \nabla \times E = -\frac{\partial B}{\partial t}}$$ ECEN, AERO
39 Ampere’s Circuital law relates the integrated magnetic field around a closed loop to the electric current passing through the loop. This law can be expressed in an integral form or differential form: the differential form is shown here. $${\displaystyle \nabla \times B = \mu _0 \left( J + \epsilon _0 \frac {\partial E} {\partial t}\right)}$$ ECEN, AERO
40 Euler’s Identity is mathematical expression containing three of the basic arithmetic operations: addition, multiplication, and exponentiation. The identity also links five fundamental mathematical constants. $${\displaystyle e^{i\pi} + 1 = 0}$$ ALL
41 The Gaussian Integral is encountered in physics and quantum field theory. This integral has a wide range of applications in engineering and science, like in computing the normalizing constant of the normal distribution. $${\displaystyle \int_{-\infty}^{\infty}e^{-x^{}}dx = \sqrt {\pi}}$$ ALL
42 Bernoulli’s Equation models incompressible fluid flow and is based on the principle that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure. $${\displaystyle p_1 + \rho \frac {V_1 ^{2}}{2} = p_2 + \rho \frac {V_2 ^{2}}{2}}$$ ALL
43 The Lift Equation states that the lift force on a body equals the lift coefficient, times the wing area, times one-half of the density of the air, times the square of the velocity. $${\displaystyle Lift = C_L \times S \times \left( \frac {1}{2} \times \rho \times \upsilon ^2\right)}$$
Or
$${\displaystyle L = \rho VT}$$
AERO
44 The Kinetic Energy of an object is the energy that it possesses due to its motion. The standard unit of kinetic energy is the joule. $${\displaystyle T = \frac {1}{2}m v ^2}$$ ALL
45 The Tsiolkovsky Rocket Equation describes the motion of a vehicle that follows the basic principle of a rocket, which is a device that can apply acceleration to itself by expelling part of its mass with high velocity. The equation relates the change of vehicle velocity to the exhaust velocity and initial and final mass of the vehicle. $${\displaystyle \Delta v = v _e \ln \frac {m_{}0}{m_{f}}}$$ AERO
46 The Laplace Transform is an integral transform that relates a function of a real variable t to a function of a complex variable s. $${\displaystyle F(s) = \int_{0}^{\infty}f(t)e^{-st}dt}$$ ALL
47 The Mohr-Coulomb Failure Criterion represents the linear envelope that is obtained from a plot of the shear strength of a material versus the applied normal stress. More generally, the Mohr–Coulomb theory is a mathematical model that describes the response of brittle materials, like concrete or rubble piles, to shear stress as well as normal stress. Most of the classical engineering materials somehow follow this rule in at least a portion of their shear failure envelope. $${\displaystyle \tau = \sigma \tan ( \phi ) + c}$$ CVEN, MSEN
48 The Darcy-Weisbach Equation is a phenomenological equation that relates the head loss, or pressure loss, due to friction along a given length of pipe to the average velocity of the fluid flow for an incompressible fluid. $${\displaystyle \frac {\Delta p}{L} = f _D \cdot \frac {\rho}{2} \cdot \frac {\langle\upsilon\rangle^{2}}{D}}$$ CVEN, MSEN
49 The Richards Equation is a nonlinear partial differential equation that models the movement of water in unsaturated soils. $${\displaystyle \frac {\partial \theta}{\partial t} = \frac {\partial}{\partial z} \left[ K(\theta)\left(\frac{\partial h}{\partial z}+1\right) \right]}$$ CVEN
50 The nth Harmonic number, which is the sum of the reciprocals of the first n natural numbers, can be approximated via the formula shown. This approximation is commonly used in the analysis of algorithms. $${\displaystyle H _n = \ln n + y + O \left( \frac {1}{n}\right)}$$ CSCE