7- (10 points) Water flows steadily through the Venturi tube shown. Consider in the passage shown that the losses are negligible. The area of section (1) is 20 cm- and that of section (2) is 10 cm. The specific mass of mercury is 13000 kg/m. The viscosity of water is equal to 0.001 Pa.s. A mercury manometer is installed between sections (1) and (2) and indicates the difference in level shown. Determine: a) The expression for calculating the flow as a function of the pressure difference (P1-P2); b) the flow rate of water flowing through the pipe. Why does the pressure change between points 1 and 2 (disregard friction)? (1) ) (2) ,0 (A) (D) h=10cm (B) (C) Hg