Pressure in Liquid - Example 2

Example 2:

Figure above shows the cross section of a sea near a seaside. Find the difference of the pressure between point A and point B. [Density of seawater = 1050kg/m³]

Answer:
Density, ρ = 1050kg/m³
Gravitational Field Strength, g = 10 N/kg

At point A:
Depth, h = 0.8 m
$P a = h a ρg+ P atm P a =(0.8)(1050)(10)+ P atm P a =8400+ P atm$
At point B:
Depth, h = 3 m
$P b = h b ρg+ P atm P b =(3)(1050)(10)+ P atm P b =31500+ P atm$
Pressure Difference
$P b − P a =(31500+ P atm )−(8400+ P atm ) =23100Pa$