Hydrostatic Pressure in Fluids

Steps:

• Total pressure at lake bottom combines atmospheric pressure and hydrostatic pressure from water.
• Hydrostatic pressure is ρ g h, where ρ is water density, g is gravity, and h is depth.
• Atmospheric pressure is denoted as p (or P).
• Thus, total pressure formula is p + ρ g h, requiring g, ρ, and p.

Why A is correct:

• Matches the formula P_total = p + ρ g h, where p is atmospheric pressure, ρ is density, and g is gravitational acceleration.

Why the others are wrong:

• B omits ρ (density), essential for hydrostatic component.
• C omits g (gravity), needed to compute weight of fluid column.
• D omits p (atmospheric pressure), ignoring surface pressure contribution.

Final answer: A