Root-mean-square speed

2013-06-23T07:39:47Z

159.205.232.177:

[[File:NGC 4402 Hubble heic0911c.jpg|thumb|300px|right|Ram pressure stripping in [[NGC 4402]] as it falls towards the [[Virgo Supercluster]] (off image, bottom left). Note the [[cosmic dust|dust]] (brown) trailing behind the galaxy.]]

In [[physics]], '''ram pressure''' is a [[pressure]] exerted on a body which is moving through a [[fluid]] medium. It causes a strong [[drag (physics)| drag]] force to be exerted on the body. It is given by:

<math>P= \rho v^2</math> <ref> Relativistic Astrophysics and Cosmology, A Fabian and Lasenby, University of Cambridge Lecture Notes, Michaelmas 2010. </ref>

where P is the pressure, <math>\rho</math> is the density of the fluid and v the velocity of the body. Alternatively the body can be stationary and v describe the velocity of the fluid, e.g. the [[solar wind]].

For example, a [[meteor]] traveling through the Earth's atmosphere produces a [[shock wave]] generated by the extremely rapid compression of air in front of the meteoroid. It is primarily this ram pressure (rather than [[friction]]) which heats the air which in turn heats the meteoroid as it flows around it.<ref>Plait, p.1</ref>

[[Galaxy|Galaxies]] in [[galaxy cluster|clusters]] experience ram pressure as they move through the [[intracluster medium]]; it is capable of stripping the galaxy of much of its [[interstellar gas]].<ref> Grebel, Gallagher, Harbeck, pp.1-15</ref>

==Notes==

<div class="references-small"><references/></div>

==References==
*Grebel, Gallagher, Harbeck (2003) [http://arxiv.org/abs/astro-ph/0301025 ''The Progenitors of Dwarf Spheroidal Galaxies'' ] ArXiv.org. retrieved Nov. 2007

== External links ==

*[http://arxiv.org/abs/physics/0609156 Educational materials on air resistance]

{{astronomy-stub}}
[[Category:Fluid dynamics]]

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Root-mean-square speed