2007-06-19 05:49:45 · 8 answers · asked by SWETA 2 in Science & Mathematics ➔ Chemistry
Certain types of barometers use the height of mercury liquid as reference indicator of pressure. They are in the shape of a U with one end open to atmosphere and the other end is a vacuum. The weight of the mercury wil pull it from the closed end and down to the u bend. If both sides of the barometer were seeing a vacuum, the level of mercury would be of equal hieghts on both sides. But since Atmostpheric pressure pushes down on the mercury on the open side, that side is lower. The 77mm is the height difference between the two levels. It really is a measurement which is relative to the pressure of the gas pushing on the mercury. 77mm is about one tenth of atmospheric pressure.
2007-06-19 06:27:04 · answer #1 · answered by billgoats79 5 · 0⤊ 0⤋
When mercury is put into a long skinny tube and then inverted into a bowl the mercury will have a height in the tube. It is held by the pressure of the air on the bowl and measures the air pressure.
2007-06-19 06:05:16 · answer #2 · answered by Barkley Hound 7 · 0⤊ 0⤋
A pressure of 1 atm is given by 76 mm of Hg (Mercury)
Thus 77 mm is 77/76 atm.
2007-06-19 05:59:20 · answer #3 · answered by ag_iitkgp 7 · 0⤊ 3⤋
that would be pressure. 1mm Hg=1 Torr (one of the pressure measurement units)
1 Pa = 1 N/m² = 10^−5 bar = 10.197×10^−6 at = 9.8692×10^−6 atm=7.5006×10^−3 Torr
2007-06-19 05:57:53 · answer #4 · answered by Anonymous · 0⤊ 0⤋
In addition to the answer given by "Aaron", refer to the following link to know more about barometers and how pressure is computed using them:
What is a barometer?
http://en.wikipedia.org/wiki/Barometer
How a barometer measures air pressure:
http://www.usatoday.com/weather/wbaromtr.htm
2007-06-19 05:59:38 · answer #5 · answered by ping_anand 3 · 0⤊ 0⤋
77mm of mercury means that the pressure acting on that body is equal to the pressure acting on a mercury barometer and producing a height of 77mm of mercury in the barometer tube.standard pressure is 760mm of mercury.
2007-06-19 05:54:39 · answer #6 · answered by Anonymous · 4⤊ 0⤋
77mmHg means the pressure and it can be expressed in pascals or mm of mercury.
2007-06-19 05:56:32 · answer #7 · answered by Anonymous · 0⤊ 0⤋
77 milimeters...is volume...is a unit of length in the metric system, equal to one thousand of a metre
2007-06-19 05:55:33 · answer #8 · answered by rokeroker 1 · 0⤊ 3⤋