Question

A 0.50 meter thick layer of oil of density 0.8 g/cm3 floats on a 1.20 meter thick layer
of water. What is the pressure at the bottom of the water layer?
(take g =10 m/s2 ;density of water = 1000 kg/m3)

Answer 1

we know that the pressure is given as

P = hρg

now the absolute pressure at the bottom of the container would be some of both layers of liquid

so,

P = P_oil + P_water

here

P_o = h_oρ_og

where

h_o = 0.5 m

ρ_o = 0.8 g/cm³ = 800 kg/m³

and

P_o = h_wρ_wg

where

h_w = 1.2 m

ρ_w = 1000 kg/m³

thus, we get

P = (0.5 x 800 x 9.81) + (1.2 x 1000 x 9.81)

= 3924 + 11772

thus, the pressure at te bottom will be

P = 15696 Pa