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)

Answer 1

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 = ρ_w = 1000 kg/m³
P’ = h’ρ_wg
But, P’ = P
h’ρ_wg = hρg
h’ρ_w = hρ
h’ = `"hρ"/"ρ"_"w"=(0.7xx13600)/1000` = 9.52 m