Problem 9.67

กำหนดให้ \(ρ = 1,000 kg/m^{3}, r_{1} = 5.0 cm, r_{2} = 2.5 cm, v_{2} = 20 m/s,\)

\(y_{1} = y_{2} = 0 m, P_{2} = 1.0\times 10^{5} Pa\) และ \(g = 9.80 m/s^{2}\)

จาก \(A_{1}v_{1} = A_{2}v_{2}\)

\(\pi r_{1}^{2}v_{1} = \pi r_{2}^{2}v_{2}\)

\(v_{1} = 5.0 m/s\)

จาก\(P_{1}+\frac{1}{2}ρv_{1}^{2}+ρgy_{1}=P_{2}+\frac{1}{2}ρv_{2}^{2}+ρgy_{2}\)

\(P_{1}=P_{2}+\frac{1}{2}ρ(v_{2}^{2}-v_{1}^{2})\)

\(P_{1} = 2.9\times 10^{5} Pa \;\blacksquare\)