Pressure at free surface of a water lake is P₁, while at a point at depth h below it's free surface is P₂. (a) How are P₁ and P₂ related ? (b) Which is more P₁ or P₂ ?

(a) As we know,

Total pressure in a liquid at a depth h is P₂

= atmospheric pressure acting on the surface (P₁) + pressure due to liquid column (h ρ g)

= P₁ + h ρ g

Hence,

P₂ = P₁ + h ρ g

(b) From the above expression we observe that,

P₂ > P₁