Question

At a given place, a mercury barometer records a pressure of 0.70 m of Hg. What would be the height of water column if mercury in barometer is replaced by water? Take density of mercury to be  = 13.6 × 10³ kg m^-3.

Answer 1

Relative Density of Hg = 1.36 = `13.6 xx 10^3  "kgm"^-3` 

Acceleration due to gravity , g = 9.8  `"ms"^-2`

Height of mercury column = 0.70 m

∴ Pressure , P = hρg

or , P = `(0.7)(1.36 xx 10^3)(9.8)` pascal

or , P = `93.3 xx 10^3` Pa

Let h be the height of water column

Then , P = h (density of water) g

or , `93.3 xx 10^3 = "h" xx 10^3 xx 9.8`

or , h = 9.52 m