Water at pressure 1.200 × 10⁵ Pa flows at 1.0 m/s in a horizontal pipe of area 10 cm², which narrows to 5.0 cm². What is the pressure in the narrow part (density of water = 1000 kg/m³)?
Correct answer C. 1.185 × 10⁵ Pa
Explanation
Continuity gives v₂ = 2.0 m/s. Then P₂ = P₁ − ½ρ(v₂² − v₁²) = 1.200 × 10⁵ − ½ × 1000 × 3.0 = 1.185 × 10⁵ Pa. The pressure falls, not rises.
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