An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Position, in a series arranged in order, on the basis of some principle of arrangement, with reference to the other items or values in the series.

M.E., from O.E. ranc "proud, overbearing, showy," from O.Fr. renc, ranc, rang "row, line;" cf. Dan. rank "right, upright," Ger. rank "slender," O.N. rakkr "straight, erect," perhaps from PIE *reg- "to stretch, straighten," cognate with Pers. râst, → right.

Rotbé, loan from Ar. ratbat "rank."

A temperature scale in which the degree intervals are the same size as in the → Fahrenheit scale, but 0 is set at absolute zero, -459.69 °F. Therefore, 1 degree Rankine is equal to exactly 5/9 → kelvin. It was formerly used by engineers in English-speaking countries, but is now obsolete. See also → Celsius scale, → Kelvin scale, → Reaumur scale.

Named for the British physicist and engineer William John Rankine (1820-1872); → scale.

Hydrodynamics → conservation laws (which can be extended to → magnetohydrodynamics, MHD) which describe the physical conditions of material across a → shock front. A fluid is completely described by its velocity, density, pressure, specific heat ratio, and magnetic field (in the MHD case). Mass, momentum, and energy fluxes are conserved in the shock, leading to the Rankine-Hugoniot relations. Also called Rankine-Hugoniot jump conditions. See also → jump condition.

Named after William John Rankine, → Rankine scale, and Pierre Henri Hugoniot, → Hugoniot curve; → condition.

The total number of → contravariant and → covariant indices (→ index) of a → tensor.

→ tensor; → rank.