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Use mercury barometer to fing height of building

  1. Nov 29, 2005 #1
    A mercury barometer reads 700.0 mm on the roof of a building and 715 mm on the ground. Assuming a constant value of 1.29 kg/m3 for the density of air, determine the height of the building.
    My setup was finding the difference in the pressures for mercury and get 15 mm Hg
    Then use Hg density = 136000 to get a pressure using P=pgh
    So P will equal 1999200
    then subtract atmosphere pressure and divide the result by 12.642 (pg)
    But the answer is wrong... Where did I go astray?
  2. jcsd
  3. Nov 30, 2005 #2


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    I haven't checked anything else, but the specific gravity of mercury is 13.6, so its density is 13.6 times greater than water, so density of mercury is 13.6*10^3 = 13,600 kg/m^3.
    You have 10 times that value, 136,000, or that a typo ??
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