A liquid of density 1000 kg m⁻³ flows steadily through a horizontal tube. Area at A is 1.5 cm², area at B is 25 mm², and speed at B is 60 cm s⁻¹. The pressure difference Pₐ - Pʙ is:

Question

G1 Physics · Accepted Answer

Continuity: Aₐvₐ = Aʙvʙ Aₐ=1.5 cm² Aʙ=25 mm²=0.25 cm² Thus, vₐ = (0.25/1.5)(60) = 10 cm s⁻¹ = 0.10 m s⁻¹ vʙ=0.60 m s⁻¹. For a horizontal tube, Bernoulli gives: Pₐ-Pʙ = (1/2)ρ[vʙ²-vₐ²] = (1/2)(1000)(0.36-0.01) = 175 Pa Hence option A follows.