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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 53 Search : sure
Roemer's measurement
  اندازه‌گیری ِ رؤمر   
andâzegiri-ye Rømer

Fr.: mesure de Rømer   

The first successful measurement of the → speed of light carried out by the Danish astronomer Ole Rømer in 1675 at Paris Observatory. Astronomers knew that the mean period of revolution for Jupiter's innermost satellite → Io (Jupiter I) was 42.5 hours. During this period Io was sometimes eclipsed by Jupiter. Astronomers expected that if Io was visible at some time it must be visible 42.5 hours later. But Ole Rømer discovered that there were many irregularities in Io's orbital period. Sometimes Io appeared too early and other times too late in relation to the expected times. The irregularities repeated themselves precisely at a one-year interval, which meant that they must be connected to the Earth's rotation around the Sun. Rømer attributed this difference in time to the additional distance the light from Io had to travel at different times, and used this information to calculate the speed of light. He found that it takes light 22 minutes to traverse the Earth's orbital diameter; the correct figure was later determined to be 16 minutes and 40 seconds. Rømer was able to measure the speed of light to be 230,000 km s-1. Although this figure was very close to the currently accepted value of 300,000 km s-1, it was rejected by the scientific community of the time, who assumed it to be much too high a figure.

Ole Rømer (1664-1710); → measurement.

solar radiation pressure
  فشار ِ تابش ِ خورشید   
fešâr-e tâbeš xoršid (#)

Fr.: pression du rayonnement solaire   

The → radiation pressure of solar photons, which pushes a comet's dust outward to form a → dust tail.

solar; → radiation; → pressure.

sound pressure
  فشار ِ صدا   
fešâr-e sedâ

Fr.: pression de son   

The periodic fluctuation above and below atmospheric pressure created by an oscillating body which provides the → sound power. Instantaneous sound pressure is the peak value of air pressure.

sound; → pressure.

stagnation pressure
  فشار ِ ناروانی   
fešâr-e nâravâni

Fr.: pression de stagnation   

The sum of → static pressure and → dynamic pressure in the → Bernoulli equation.

stagnation; → pressure.

standard temperature and pressure (STP)
  دما و فشار ِ استانده   
damâ o fešâr-e estândé

Fr.: conditions normales de température et de pression   

1) The most commonly used definition is temperature of 273.15 K (0 °C) and pressure of 1 → atmosphere.
2) Chemistry: Temperature of 273.15 K (0 °C) and pressure of 105  → pascal (Pa)s (1 → bar). International Union of Pure and Applied Chemistry (IUPAC) recommends that the former use of the pressure of 1 atm as standard pressure (equivalent to 1.01325 × 105 Pa) should be discontinued.

standard; → temperature; → pressure.

static pressure
  فشار ِ ایستا   
fešâr-e istâ

Fr.: pression statique   

In → fluid mechanics, the → pressure felt by an object suspended in a → fluid and moving with it. This pressure is called static because the object is not moving relative to the fluid. See also → dynamic pressure.

static; → pressure.

sure
  تنز   
tenz

Fr.: sûr   

Free from doubt as to the reliability, character, action, etc., of something (Dictionary.com).

M.E. sur(e), from M.Fr. sur, O.Fr. seur "safe, secure; trustworthy," from L. securus "free from care, untroubled, safe," from *se cura, from se "free from" + cura "care."

Tenz, from (Fine-e Bandar Abbâs) tenz "firm, fixed, solid," variant tereng; (Tabari) tereng, təreq "firm, fixed;" (Baxtiyâri) teng "firm;" cf. Baluci tranj-, dranjit, tranjit/drannj-, draht, dratk "to hang up;" ultimately from Proto-Ir. *dra(n)j- "to fix, fasten, hold;" Av. drənj- (draž-) "to fix, fasten, hold;" Parthian (*abi-) 'bdrynj- "to be sure, secure; make certain;" Khotanese drys- "to hold;" cognate with Gk. drassomai "I hold (with the hand), take;" O.Irish dringid "he climbs;" M.Welsh dringo "to climb;" PIE *dregh- "to hold, fasten."

surely
  تنزانه   
tenzâné

Fr.: sûrement   

Without doub; certainly; to be sure; for sure.

sure; → -ly.

surety
  اتیماری   
atimâri

Fr.: caution, garantie, sureté   

1) Security against loss or damage or for the fulfillment of an obligation, the payment of a debt, etc.; a pledge, guaranty, or bond.
2) The state or quality of being sure (Dictionary.com).

M.E. surte, from M.Fr., from O.Fr. seurte "a promise, pledge, guarantee; assurance, confidence;" from L. securitas "freedom from care or danger, safety," from securus, → secure.

thermal pressure
  فشار ِ گرمایی   
fešâr-e garmâyi (#)

Fr.: pression thermale   

The ordinary pressure in a gas that is due to motions of particles and can be attributed to the object's → temperature.

thermal; → pressure.

total pressure
  فشار ِ هماک   
fešâr-e hamâk

Fr.: pression totale   

The sum of → static pressure, → dynamic pressure, and → hydrostatic pressure in the → Bernoulli equation.

total, → pressure.

vapor pressure
  فشار ِ بخار   
fešâr-e boxâr

Fr.: pression de vapeur   

The equilibrium pressure of a vapor above its condensed phases (liquid or solid). In other words, the pressure of the vapor resulting from evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container. The vapor pressure varies with the temperature. As the temperature increases its the vapor pressure also increases, and conversely. The temperature at which the vapor pressure is equal to the atmospheric pressure is called the → boiling point. For example, at 20 °C, water would boil at a pressure of about 0.023 atm, or about a fortieth of atmospheric pressure.

vapor; → pressure.

velocity pressure
  فشار ِ توانیک   
fešâr-e tavânik

Fr.: pression dynamique   

dynamic pressure.

velocity; → pressure.

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