3. Basic Equations: a.) Continuity: mass in = mass out b.) Bernoulli’s Eqn. Total pressure is constant throughout i.e. ½ ρ V 2 + P =constant For a fluid flowing in a horizontal pipe. m 1 =m 2 & m = ρ AV .’. ρ 1 A 1 V 1 = ρ 2 A 2 V2 For incompressible fluids ρ 1 = ρ 2 Thus A 1 V 1 = A 2 V 2