Variation of pressure with depth
Fluid statics · Physics
Bernoulli pipe
Interactive 3DNarrow the pipe and the flow speeds up while pressure drops — Bernoulli in action.
Controls
Drag the sliders or type a value — the simulation updates live.
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0.3×1×
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0.5×3×
Study notes
A diver is 25 m below the surface of the sea (ρ = 1025 kg/m³). Find the total pressure on the diver. (P₀ = 1.01 × 10⁵ Pa, g = 9.8 m/s²) Step 1: Gauge pressure from water: ρgh = 1025 × 9.8 × 25 = 251,125 Pa ≈ 2.51 × 10⁵ Pa. Step 2: Add atmospheric pressure: P = P₀ + ρgh = 1.01 × 10⁵ + 2.51 × 10⁵ = 3.52 × 10⁵ Pa. Step 3: In atmospheres: 3.52 × 10⁵ / 1.01 × 10⁵ ≈ 3.5 atm. Answer: ≈ 3.5 × 10⁵ Pa (≈ 3.5 atm). The diver's body withstands this because internal body pressure balances it — the danger is in pressure changes, not the pressure itself.