Answer:
V = 1060.8 cm³
Explanation:
we know that the pressure,
P = density x gravity x depth
ρm is the density of mercury
ρw is the density of water
the pressure due to mercury P₁= (ρm) g h₁
the pressure due to water P₂ = (ρw) g h₂
the total pressure
P = P₁ + P₂
P = (ρm) g h₁ + (ρw) g h₂
but the total pressure is double the pressure due to mercury.
(ρm) g h₁ =(ρw) g h₂
h₂ = 81.6 cm
the height of the water is 81.6 cm
the volume
V = height x area
V = 81.6 x 13
V = 1060.8 cm³
the volume of water must be added to double the gauge pressure is V = 1060.8 cm³