Ram pressure

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

$P=\rho v^{2}$ ^[1]

where P is the pressure, $\rho$ 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.^[2]

In the case of a galaxy moving through the intergalactic gas, the ram pressure is capable of stripping the galaxy of much of its interstellar gas.^[3]

Notes

^ Relativistic Astrophysics and Cosmology, A Fabian and Lasenby, University of Cambridge Lecture Notes, Michaelmas 2010.
^ Plait, p.1
^ Grebel, Gallagher, Harbeck, pp.1-15

References

Grebel, Gallagher, Harbeck (2003) The Progenitors of Dwarf Spheroidal Galaxies ArXiv.org. retrieved Nov. 2007
Plait, Philip (2002), Top 5 Cosmic Myths #4:Meteors are heated by friction as they pass through the atmosphere Retrieved 2011-05-31

External links

Educational materials on air resistance

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[1] Relativistic Astrophysics and Cosmology, A Fabian and Lasenby, University of Cambridge Lecture Notes, Michaelmas 2010.

[2] Plait, p.1

[3] Grebel, Gallagher, Harbeck, pp.1-15

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