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Rarefaction (ecology) In ecology, rarefaction is a technique to assess species richness from the results of sampling. Rarefaction allows the calculation of species richness for a given number of individual samples, based on the construction of so-called rarefaction curves. This curve is a plot of the number of species as a function of the ...
Compression (physics) In mechanics, compression is the application of balanced inward ("pushing") forces to different points on a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions. [1] It is contrasted with tension or traction, the application of balanced outward ...
In physics, a mechanical wave is a wave that is an oscillation of matter, and therefore transfers energy through a material medium. [1] (. Vacuum is, from classical perspective, a non-material medium, where electromagnetic waves propagate.) While waves can move over long distances, the movement of the medium of transmission—the material—is ...
Rarefaction is the reduction of an item's density, the opposite of compression. [1] Like compression, which can travel in waves (sound waves, for instance), rarefaction waves also exist in nature. A common rarefaction wave is the area of low relative pressure following a shock wave (see picture). Rarefaction waves expand with time (much like ...
The compressive strength of the material corresponds to the stress at the red point shown on the curve. In a compression test, there is a linear region where the material follows Hooke's law. Hence, for this region, =, where, this time, E refers to the Young's modulus for compression. In this region, the material deforms elastically and returns ...
In physics, magnetosonic waves, also known as magnetoacoustic waves, are low-frequency compressive waves driven by mutual interaction between an electrically conducting fluid and a magnetic field. They are associated with compression and rarefaction of both the fluid and the magnetic field, as well as with an effective tension that acts to ...
A schematic diagram of a shock wave situation with the density , velocity , and temperature indicated for each region.. The Rankine–Hugoniot conditions, also referred to as Rankine–Hugoniot jump conditions or Rankine–Hugoniot relations, describe the relationship between the states on both sides of a shock wave or a combustion wave (deflagration or detonation) in a one-dimensional flow in ...
Diagram showing displacement of the Sun 's image at sunrise and sunset. Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. [1] This refraction is due to the velocity of light through air decreasing ...