Ram pressure
Encyclopedia
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:
where P is the pressure,
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.
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.
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, ram pressure is a pressure exerted on a body which is moving through a fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
medium. It causes a strong drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
force to be exerted on the body. It is given by:
where P is the pressure,
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 windSolar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
.
For example, a meteor
METEOR
METEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...
traveling through the Earth's atmosphere produces a shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
generated by the extremely rapid compression of air in front of the meteoroid. It is primarily this ram pressure (rather than friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
) which heats the air which in turn heats the meteoroid as it flows around it.
In the case of a galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
moving through the intergalactic gas, the ram pressure is capable of stripping the galaxy of much of its interstellar gas.