# Calculations

**Aerodynamics**- Drag Coefficient
- A dimensionless value that allows the comparison of shape and orientation of different bodies.
- Kinematic Viscosity
- The dynamic viscosity of a fluid divided by the fluid density.
- Vehicle Aerodynamic Drag
- Resistance of a vehicle body to motion through the air.
- Viscosity
- A measure of the internal friction within a fluid.

**Algebra**- Antilogarithm
- x=b
^{y}is called the antilogarithm of y to the base b. - Briggsian Logarithm
- Another name for the Common Logarithm.
- Common Logarithm
- Logarithm in which the base is 10.
- Cubic Equation
- An equation of the third order.
- Logarithm
- The power to which a base must be raised to yield a given number.
- Napierian Logarithm
- Another name for the Natural or Common Logarithm.
- Natural Logarithm
- Logarithm in which the base is e.
- Quadratic Equation
- An equation of the second order.

**Architectural Acoustics**- Acoustic Cavity
- The acoustics of enclosed volumes are important when considering sound propagation within the volume.
- A Weighting
- This is the most generally used filter when making overall noise measurements.
- Cavity Acoustics
- The acoustics associated with enclosed volumes.
- Decibel
- The human ear responds logarithmically and it is convenient to deal in logarithmic units in audio systems.
- Room Modes
- Frequencies at which sound waves in a room resonate (in the form of standing waves), based on the room dimensions.
- Sound Transmission Class
- In acoustics, a single number rating for describing sound transmission loss of a wall or partition.

**Architecture**- Room Modes
- Frequencies at which sound waves in a room resonate (in the form of standing waves), based on the room dimensions.

**Audio**- Acoustic Cavity
- The acoustics of enclosed volumes are important when considering sound propagation within the volume.
- A Weighting
- This is the most generally used filter when making overall noise measurements.
- Bark
- The Bark is the standard unit corresponding to one critical band width of human hearing.
- B Weighting
- The B-weigthing curve approximately follows the 70 phon curve.
- Circular Frequency
- The frequency of a steady recurring phenomenum in radians per second.
- C Weighting
- The C-weighting curve approximately follows the 100 phon curve.
- dBA
- A sound-level meter reading with an A-weighting network simulating the human-ear response at a loudness level of 40 phons.
- dBB
- A sound-level meter reading with a B-weighting network simulating the human-ear response at a loudness level of 70 phons.
- Decibel
- The human ear responds logarithmically and it is convenient to deal in logarithmic units in audio systems.
- Quarter Wave Tube
- A resonator used most commonly on automotive air intake systems to reduce resonance.
- Sound Transmission Class
- In acoustics, a single number rating for describing sound transmission loss of a wall or partition.
- Speed of Sound
- Depends on the elastic and inertial properties of the particular medium.

**Automotive**- Engine Radiated Noise
- Some empirical noise prediction models have been derived from a sample of 1m radiated engine noise measurements.
- Fuel Consumption
- Definitions of fuel consumption calculations.
- litres per 100km
- Unit of fuel consumption used in the automotive industry.
- mile per gallon
- Fuel consumption.
- Wheel
- The Mesopotamians are credited with the invention of the wheel.

**Civil Engineering**- Cantilever Beam
- A beam that is held in an encastre at one end whilst the other end is unsupported.

**Classical Mechanics**- Acceleration
- The change in velocity divided by the time it takes to make the change.
- Angular Frequency
- The frequency of a steady recurring phenomenum in radians per second.
- Angular Momentum
- A vector quantity giving the rotational momentum.
- Angular Velocity
- The rate of change of angle turned in radians.
- Escape Velocity
- This is the initial velocity that an object would have to have if projected from the surface of a body (e.g. Earth) to reach infinity before coming to rest.
- Kinetic Energy
- The energy that a body possesses solely because it is moving.
- Linear Momentum
- A vector quantity equal to the product of an object's mass and its velocity.
- Torque
- The torque or turning moment acting on a body is defined as the product of the magnitude of the force and the perpendicular distance of the line of action of the force from the axis about which the body is being rotated.

**Electronics**- B
- An abbreviation of bel, the logarithm of the ratio of two powers. The decibel is one tenth of a bel.
- bel
- The bel is the logarithm of the ratio of two powers, and the decibel is one tenth of a bel.
- Decibel
- The human ear responds logarithmically and it is convenient to deal in logarithmic units in audio systems.
- Resistance
- The electrical resistance of a conductor.
- Resistor
- Passive component with a known resistance. The value of resistance is usually shown by a set of coloured bands on the body of the component.

**Engines**- Engine Radiated Noise
- Some empirical noise prediction models have been derived from a sample of 1m radiated engine noise measurements.
- Fuel Consumption
- Definitions of fuel consumption calculations.

**Fluid Dynamics**- Drag Coefficient
- A dimensionless value that allows the comparison of shape and orientation of different bodies.
- Dynamic viscosity
- That molecular property of a fluid which enables it to support tangential stresses for a finite time and thus to resist deformation.
- Kinematic Viscosity
- The dynamic viscosity of a fluid divided by the fluid density.
- Vehicle Aerodynamic Drag
- Resistance of a vehicle body to motion through the air.
- Viscosity
- A measure of the internal friction within a fluid.

**Geometry**- Circle
- The set of points equidistant from a given point.
- Sphere
- Basic calculations of the properties of a sphere.
- Square
- A number raised to the power 2 ie 2 x 2 = 2
^{2}= 4. Also, a 2 dimensional figure with the height and width having the same lengths,and at right angles to each other.

**Mathematics**- Angular Frequency
- The frequency of a steady recurring phenomenum in radians per second.
- Averaging
- In any process it is often necessary to average a number of measurements to gain any confidence in the measured value.
- Cylinder
- A right angle circular cylinder.
- Factorial
- Definition of factorial.
- ln
- Abbreviation of Natural Logarithm.
- log
- Abbreviation of Logarithm.
- Pythagoras Theorem
- The Square on the Hypotenuse is equal to the sum of the squares of the other two sides.
- Square
- A number raised to the power 2 ie 2 x 2 = 2
^{2}= 4. Also, a 2 dimensional figure with the height and width having the same lengths,and at right angles to each other. - Square Root
- The square root of a number is a number that when multiplied by itself equals the number that the square root is being taken of.

**Mechanical Engineering**- Cantilever Beam
- A beam that is held in an encastre at one end whilst the other end is unsupported.
- Cutting Speed
- The surface speed of the workpiece in a lathe or a rotating cutter.
- Froude Number
- A dimensionless number used in the study of fluid flow problems with models.
- Leaf Springs
- Either a simple beam used as a spring or laminations of steel.
- Moments of Inertia
- Principal axes for bodies of uniform density.
- mpg
- Abbreviation of mile per gallon.
- Prandtl Number
- A dimensionless group often used in heat exchange calculations.
- Quarter Wave Tube
- A resonator used most commonly on automotive air intake systems to reduce resonance.
- Reynolds Number
- This is a non-dimensional number (consistent units) which describes whether fluid flow is laminar, turbulent, or transitional between the two.
- Springs
- The physics of simple springs - helical and beam forms.
- Thin Rod
- The moment of inertia of a thin rod.
- Torque
- The torque or turning moment acting on a body is defined as the product of the magnitude of the force and the perpendicular distance of the line of action of the force from the axis about which the body is being rotated.
- Wheel
- The Mesopotamians are credited with the invention of the wheel.

**Noise & Vibration**- Acoustic Cavity
- The acoustics of enclosed volumes are important when considering sound propagation within the volume.
- Angular Frequency
- The frequency of a steady recurring phenomenum in radians per second.
- Articulation Index
- A quantitative measure of the intelligibility of speech; the percentage of speech items correctly perceived and recorded.
- A Weighting
- This is the most generally used filter when making overall noise measurements.
- B
- An abbreviation of bel, the logarithm of the ratio of two powers. The decibel is one tenth of a bel.
- Bandwidth Time Product
- Used in calculating the confidence limit of a measurement.
- Bark
- The Bark is the standard unit corresponding to one critical band width of human hearing.
- bel
- The bel is the logarithm of the ratio of two powers, and the decibel is one tenth of a bel.
- B Weighting
- The B-weigthing curve approximately follows the 70 phon curve.
- Cavity Acoustics
- The acoustics associated with enclosed volumes.
- Circular Frequency
- The frequency of a steady recurring phenomenum in radians per second.
- Coincidence
- The sound radiation efficiency of a plate is dependant upon the coupling of sound waves in the air and flexural waves (vibration) in the plate. Optimum efficiency (maximum energy transfer from vibration to sound or visa versa) is achieved when the plate is vibrated such that the wavelength of flexural waves in the plate is equal to the wavelength of acoustic waves in the air.
- C Weighting
- The C-weighting curve approximately follows the 100 phon curve.
- Decibel
- Engine Radiated Noise
- Some empirical noise prediction models have been derived from a sample of 1m radiated engine noise measurements.
- Expansion Chamber
- The expansion chamber can be considered as a simple low pass filter.
- Octave
- Two frequencies are an octave apart if the ratio of the higher frequency to the lower frequency is two.
- Quarter Wave Tube
- A resonator used most commonly on automotive air intake systems to reduce resonance.
- Room Modes
- Frequencies at which sound waves in a room resonate (in the form of standing waves), based on the room dimensions.
- Single Acoustic Barrier
- A single layer acoustic barrier.
- Sound Power Level
- Of airborne sound, ten times the common logarithm of the ratio of the sound power under consideration of the standard reference power of 1 pW. The quantity so obtained is expressed in decibels.
- Sound Pressure Level
- Ten times the logarithm of the ratio of the time-mean-square pressure of a sound to the square of the reference sound pressure.
- Sound Transmission Class
- In acoustics, a single number rating for describing sound transmission loss of a wall or partition.
- Speed of Sound
- Depends on the elastic and inertial properties of the particular medium.
- Strouhal Number
- A dimensionless unit.
- Wavelength
- The shortest repetition length for a periodic wave.
- Wavenumber
- Wavenumber describes the spatial variation of waves, phase change per unit distance.

**Optics**- Pockels Cell
- A Pockels Cell is a device which contains a photo refractive crystal. When a voltage is applied to this crystal it can change the polarisation or phase of the light beam.
- Snells Law
- Snells law defines the angle of refraction of a light beam when it passes from one medium to another.

**Physics**- Averaging
- In any process it is often necessary to average a number of measurements to gain any confidence in the measured value.
- Conical Pendulum
- The motion of the wire from which the bob hangs describes the surface of a cone.
- Equations of Motion
- There are four basic equations that describe the motion of a body moving with constant acceleration.
- Frequency
- The rate of repetition of periodic motion measured in hertz (cycles per second).
- Froude Number
- A dimensionless number used in the study of fluid flow problems with models.
- Gravitational Potential
- The worrk done in bringing a unit mass from infinity to that point. The assumption being that the gravitational potential is zero at infinity.
- Gravitational Potential Energy
- The work done by the force of gravity when an object falls from a particular point in space to the location assigned the value of zero.
- Julian Day
- Instituted by J. Julius Scaliger in 1582. The Julian date is independent of various calendars and chronological events.
- Length Contraction
- An observer in motion relative to an object measures the length of that object along the direction of motion to be contracted when compared to the length measured by an observer at rest relative to the object.
- Mach Number
- The ratio of the speed of a body or flow of a fluid to the local speed of sound in the fluid.
- Moments of Inertia
- Principal axes for bodies of uniform density.
- Newton′s Law of Universal Gravitation
*Every particle in the Universe attracts every other with a force which is proportional to the product of their masses and inversely proportional to the square of their seperation.*- Ohm
- Defined as the resistance of a conductor through which a current of one ampere is flowing when the potential difference across it is one volt.
- Pendulums
- There are a number of different forms of pendulum. The main characteristic being that when the mass is displaced from it's position of rest it will oscillate at a fixed frequency.
- Prandtl Number
- A dimensionless group often used in heat exchange calculations.
- Relativistic Kinetic Energy
- The energy that a body possesses solely because it is moving.
- Resistance
- The electrical resistance of a conductor.
- Reynolds Number
- This is a non-dimensional number (consistent units) which describes whether fluid flow is laminar, turbulent, or transitional between the two.
- Simple Pendulum
- The mass hung on a fine wire, displaced from rest and released.
- Snells Law
- Snells law defines the angle of refraction of a light beam when it passes from one medium to another.
- Speed of Sound
- Depends on the elastic and inertial properties of the particular medium.
- Strouhal Number
- A dimensionless unit.
- Thin Rod
- The moment of inertia of a thin rod.
- Wavelength
- The shortest repetition length for a periodic wave.
- Wavenumber
- Wavenumber describes the spatial variation of waves, phase change per unit distance.
- Wheel
- The Mesopotamians are credited with the invention of the wheel.

**Signal Processing**- Bandwidth Time Product
- Used in calculating the confidence limit of a measurement.
- Circular Frequency
- The frequency of a steady recurring phenomenum in radians per second.

**Tools**- Cutting Speed
- The surface speed of the workpiece in a lathe or a rotating cutter.

**Transport**- Vehicle Aerodynamic Drag
- Resistance of a vehicle body to motion through the air.

**Trigonometry**- Cosine
- Trigonometric function.
- Sine
- Trigonometrical function.
- Tangent
- Trigonometric function.

**Units**- Decibel
- Pound Force Foot
- The unit of torque in the old British system of units, abbreviated lbf ft.