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.
Famous quotes containing the words ram and/or pressure:
“At one time or another, almost every politician needs an honest man so badly that, like a ravenous wolf, he breaks into a sheep-fold: not to devour the ram he has stolen, however, but rather to conceal himself behind its wooly back.”
—Friedrich Nietzsche (1844–1900)
“Much of the pressure contemporary parents feel with respect to dressing children in designer clothes, teaching young children academics, and giving them instruction in sports derives directly from our need to use our children to impress others with our economic surplus. We find “good” rather than real reasons for letting our children go along with the crowd.”
—David Elkind (20th century)