Vectors can only be added, subtracted or multiplied using mathematical procedures that take account of the co-ordinates. A vector is defined as an element of a vector space.

Vector space : vector spaces are applied throughout mathematics, science and engineering. They are the linear-algebraic notion to deal with systems of linear equations; offer a framework for Fourier expansion or provide an environment that can be used for solution techniques for partial differential equations.

Velocity : v : the rate of change of position and is a vector quantity as both speed and direction are required to define it.

The SI units are metres per second: (m/s).

v = u + at where v = velocity, u = start velocity, a = acceleration in m/s^{2} and t = time.

Velocity of Sound is usually taken to mean the Speed of Sound.

Should not be confused withSound Particle Velocity, which is the velocity of the individual particles. To add to the confusion the unit v is often included.

Vibration : mechanical
oscillations occur about an
equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random.

Vibration at Work Regulations : The Control of Vibration at Work Regulations 2005 (the Vibration Regulations), came into force on 6 July 2005 and aim to protect workers from risks to health from vibration.

Volt : V : the derived SI Unit of electric potential; the potential difference between two points on a conductor carrying a current of 1 Ampere, when the Power dissipated between these points is 1 watt

Voltage Level : LV : dB (1 V rms) : voltage relative to 1 volt, regardless of impedance.

Lv = 20 lg (V/Vo) dBV

Reference voltage Vo = 1 volt = 0 dB

Volume : V : the amount of space that an object or substance occupies, the SI unit is the cubic metre : m^{3}

Volumetric Flow Rate : Q : is the volume of fluid which passes through a given surface per unit time.

Q = v · A where v = velocity, A = area/surface and the SI units are m^{3}/s.

Volumetric Flux : q : is the Volumetric Flow Rate across a unit area. SI units m^{3}·s^{-1}·m^{-2}

Volumetric Power Density : volume based Power Density - watt/m^{3}

Volume Velocity : is the Sound Pressure divided by the Acoustic Impedance and is defined as integral, over a vibration surface, of the product of the component of Particle Velocity normal to the surface and the differential surface area.