Capillary rise and capillary action
Surface tension · 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 glass capillary of radius 0.25 mm is dipped in water (T = 0.072 N/m, θ ≈ 0°). Find the capillary rise. (ρ = 1000 kg/m³, g = 9.8 m/s²) Step 1: h = 2T·cosθ/(ρgr) = 2 × 0.072 × 1 / (1000 × 9.8 × 0.25×10⁻³). Step 2: Numerator = 0.144. Denominator = 1000 × 9.8 × 2.5×10⁻⁴ = 2.45. Step 3: h = 0.144 / 2.45 ≈ 0.0588 m ≈ 5.9 cm. Answer: ≈ 5.9 cm. Halving the radius would double the rise to ~11.8 cm — the inverse dependence on r is the key.