ρ = 1000 kg/m3, h1 = 2m, h2 = 5 m
A1 = 4 x 10-3 m2, A2 = 8 x 10-3 m2 , v1 = 1 m/s
Equation of continuity
A1 v1 = A2v2 ∴ v2 = A1 v1 / A2 = 0.5 m/s
According to Bernoulli’s theorem,
(p1 – p1) = ρg (h2 – h1) – ½ ρ (v22) – v21
Where (p1 – p2) = work done /vol. [by the pressure ]
ρg (h2 – h1) = work don/vol. [by gravity forces]
Now, work done / vol. by gravity forces
= ρg (h2 – h1) = 103 x 9.8 x 3 = 29.4 x 103 J/m3
And ½ ρ (v22 – v21 ) = ½ x 103 [1/4 – 1 ] = - 3/8 x 103 J/m3
= - 0.375 x 103 J/m3
∴ Work done / vol. by pressure
= 29.4 x 103 – 0.375 x 103 J / m3 = 29.025 x 103 j/m3