One atmosphere (1 atm) of pressure is equivalent to which of the ...

[JGIBBSON]

One atmosphere (1 atm) of pressure is equivalent to which of the following? 1. 29.9 in Hg 2. 14.7 lb/in2 3. 1034.0 g/cm2 4. 760.0 mm Hg
 
  a. 1, 2, and 3
  b. 2 and 4
  c. 1 and 3
  d. 1, 2, 3, and 4

Question 2

You obtain a mercury barometric reading of 760 mm Hg at 17 C. Using the following factor ta-ble, compute the corrected pressure.
 
   C 740 750 760
  17 2.17 2.20 2.23
  18 2.29 2.32 2.35
  19 2.38 2.41 2.44
 
  a. 223.0 mm Hg
  b. 747.7 mm Hg
  c. 757.8 mm Hg
  d. 762.3 mm Hg

[at]

Answer to Question 1

ANS: D
At sea level, the average atmospheric pressure will support a column of mercury 76 cm (760 mm) or 29.9 in in height. If we also know that mercury has a density of 13.6 g/cm3 (0.491 lb/in3), then the average atmospheric pressure (PB) is calculated as follows:
cgs units: PB = 76 cm  13.6 g/cm3 = 1034 g/cm2
fps units: PB = 29.9 in  0.491 lb/in3 = 14.7 lb/in2

Answer to Question 2

ANS: C
The U.S. Weather Bureau provides temperature correction factors for barometric readings (see Appendix 1).

[JGIBBSON]

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