(4) A liquid with a constant density (p) is flowing (as shown in figure below) at an unknown velocity (u) through a horizontal pipe of cross-sectional area (A)) at a pressure (P), and then it passes to a section of the pipe in which the area is reduced gradually to (A,) and the pressure (P2). Assume no friction losses, and turbulent flow find: 1- An expression for the pressure difference (AP) of this system. (10marks) 2- If water flows at 7.2 mh from a 50 mm to 40 mm diameter pipe. What is the pressure difference. (10marks) pl p2 un A1 02 A2