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Question
At a given place, a barometer records 70 cm of Hg. If the mercury in the barometer is replaced by water, what would be resulting in reading? (Density of Hg = 13600 kg/m3; Density of water = 1000 kg/m3)
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Solution
Height of mercury column = h = 70 cm = 0.70 m
Density of mercury = ρ= 13600 kg/m3
Acceleration due to gravity = g = 10 m/s2
Pressure = hρg
For water:
Height of water column = h’ =?
Pressure due to water column = P’
Density of water = ρw = 1000 kg/m3
P’ = h’ρwg
But, P’ = P
h’ρwg = hρg
h’ρw = hρ
h’ = `"hρ"/"ρ"_"w"=(0.7xx13600)/1000` = 9.52 m
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