[mahmoud khodary]

A1 = 0.2^2 * 3.14 /4 = 0.0314 m^2
A2 = 0.1^2 * 3.14/4 = 0.00785 m^2
P1 - P2 = 10000 Pa
Z2 - Z1 = 3 m


من معادلة الاستمرارية continuity equation
Q = A1V1 = A2V2
V2 = A1/A2 V1
V2 = 1.71 V1
V2^2 = 2.92 V1^2
من معادلة برنوللى Bernolli equation

P1 - P2 =( V2^2 - V1^2) * Den/2 - ( Z2 -Z1 ) *Den* g

10000 = V2^2 - V1^2) *1000/2 - 3*1000 * 9.81


V1 = 4.5 m/s

Q = A1 V1 = 0.0314 * 4.5

Q = 0.14 m^3 /s