CONTINUITY EQUATION Fluid FlowAs shown in Figure 1 the pressure at different levels in the tank varies and this causes the fluidto leave the tank at varying velocities. Pressure was defined to be force per unit area. In thecase of this tank, the force is due to the weight of the water above the point where the pressureis being determined.Example:Pressure =^{Force}Area=^{Weight}AreaP =m gA g_{c}=r V gA g_{c}where:m = mass in lbmg = acceleration due to earth’s gravity 32.17ftsec^{2}g_{c} = 32.17lbm ftlbf sec^{2}A = area in ft^{2}V = volume in ft^{3}r = density of fluid inlbmft^{3}The volume is equal to the cross-sectional area times the height (h) of liquid. Substitutingthis in to the above equation yields:P =r A h gA g_{c}P =r h gg_{c}HT-03 Page 4 Rev. 0

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