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In acoustics, Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity.It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a rate α given by = where η is the dynamic viscosity coefficient of the fluid, ω is the sound's angular frequency, ρ is the fluid ...
The product of and from the above formula is known as the characteristic acoustic impedance. The acoustic power (energy per second) crossing unit area is known as the intensity of the wave and for a plane wave the average intensity is given by I = q 2 / ( ρ c ) {\displaystyle I=q^{2}/(\rho c)\,} , where q {\displaystyle q\,} is the root mean ...
In very deep water they can be lowered on cables from the surface. The primary usage is for oceanography. [4] The instruments can also be used in rivers and canals to continuously measure the discharge. Mounted on moorings within the water column or directly at the seabed, water current and wave studies may be performed. They can stay ...
In oceanography, the sverdrup (symbol: Sv) is a non-SI metric unit of volumetric flow rate, with 1 Sv equal to 1 million cubic metres per second (264,172,052 US gal/s). [1] [2] It is equivalent to the SI derived unit cubic hectometer per second (symbol: hm 3 /s or hm 3 ⋅s −1): 1 Sv is equal to 1 hm 3 /s.
A simplified version of the definition is: The k v factor of a valve indicates "The water flow in m 3 /h, at a pressure drop across the valve of 1 kgf/cm 2 when the valve is completely open. The complete definition also says that the flow medium must have a density of 1000 kg/m 3 and a kinematic viscosity of 10 −6 m 2 /s, e.g. water. [clarify]
The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m 2). One application is the noise measurement of sound intensity in the air at a listener's location as a sound energy quantity. [3] Sound intensity is not the same physical quantity as sound pressure. Human hearing is sensitive to sound pressure which is ...
The hertz is defined as one per second for periodic events. The International Committee for Weights and Measures defined the second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom" [3] [4] and then adds: "It follows that the hyperfine splitting in the ground state of the ...
Wavenumber has dimensions of reciprocal length, so its SI unit is the reciprocal of meters (m −1). In spectroscopy it is usual to give wavenumbers in cgs unit (i.e., reciprocal centimeters; cm −1 ); in this context, the wavenumber was formerly called the kayser , after Heinrich Kayser (some older scientific papers used this unit ...