Question

At a given place a mercury barometer records a pressure of 0.70m 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 ×10pawer3 kg m-3 .

Answer 1

Here h1 = 0.70m, d1 = 13.6 g = 9.8 (for mercury)

h2 = ?, d2 = 1, g = 9.8 (for water)

As the pressure measured is same in both the cases

P1 = P2

= h1 d1 g = h2 d2 g = (h1 d1 g)/(d2 g) = h2 (As pressure P = hdg)

Putting values we get

h2 = (0.70 x 13.6 x9.8)/ (1x 9.8 )

= h2 = (0.70 x 13.6 x 9.8)/9.8

= h2 = 0.70 x13.6 =9.52m