Question

Which would exert more pressure: column of water 20 cm high or column of mercury 1.5 cm high? (density of Hg = 13.6 g/cubic cm) (ii) hiiWhat height of mercury would exert the same pressure as the water column​

Answer 1

Answer:

i. Mercury column height = 1.5 cm

= 0.015 m

Density (p) of mercury = 13.6 g/cc

= 13600 kg/m³

Acceleration due to gravity (g) = 9.8 m/s

Pressure (mercury) = hpg

= (0.015*13600*9.8) Pa

= 1999.2 Pa

Water column height = 20 cm

= 0.2 m

Density of water = 1000 kg/m³

Pressure (water) = hpg

= 0.2*1000*9.8 Pa

= 1960 Pa

So, mercury will exert more pressure.

ii. Let's assume the water height to be 20 cm or, 0.2 m,

Pressure of mercury = Pressure of water

= h₁p₁g = h₂p₂g

=  h₁ = (h₂p₂g) / (p₁g)

= h₁ = (0.2*1000*9.8) / (13600*9.8)

= h₁ = 1960/133280

= h₁ = 0.0014 m

or,

= h₁ = 0.14 cm

So, mercury column should have the height of 0.14 cm for its pressure to be equal for a water column of 20 cm.

Hope this helps.