millimeter of mercury

Thân thiện

Definition

1. Noun:
   • A unit of pressure: A millimeter of mercury is a unit of pressure equal to the pressure exerted by a column of mercury one millimeter high at 0°C under standard gravity. It is approximately equal to 0.001316 atmosphere or 133.322 pascals.

Usage

• The "millimeter of mercury" is a traditional, non-SI unit used primarily in medicine (e.g., for blood pressure), physiology, and meteorology (e.g., for barometric pressure).
• It is often abbreviated as mmHg, where "Hg" is the chemical symbol for mercury.
• This unit is used to quantify pressure, particularly fluid pressure in closed systems.

Examples

• Noun:
  • A normal blood pressure reading is often stated as 120 over 80 millimeters of mercury.
  • The atmospheric pressure dropped to 760 millimeters of mercury.
  • The experiment required a vacuum of 50 mmHg.

Advanced Usage

• "torr": In scientific contexts, one millimeter of mercury is approximately equal to one torr (1 mmHg ≈ 1.000000142466321 torr). The torr is named after Evangelista Torricelli, the inventor of the barometer.
  • The pressure in the chamber was reduced to a few torr.

Variants and Related Words

• mmHg: The standard abbreviation.
• torr: A closely related unit of pressure, essentially equivalent for most practical purposes.
• inHg (inches of mercury): A larger unit of pressure using the same principle, common in aviation and older barometers.

Synonyms

• torr: (Near synonym, with a precise technical definition that is nearly identical for most applications.)

Notes on Meaning

• The "millimeter of mercury" is a manometric unit, meaning it is defined by the height of a liquid column. Its value depends on the density of mercury and the acceleration due to gravity.
• While largely superseded by the pascal (the SI unit) in many scientific fields, it remains deeply entrenched in medical practice worldwide.

Học thuật

Noun

1. a unit of pressure equal to 0.001316 atmosphere; named after Torricelli

Từ đồng nghĩa

• torr
• mm Hg