1) Two pipes are connected together in series. The diameter of one pipe is twice the diameter of the second pipe. With liquid flowing in the pipes, the velocity in the large pipe is 4 m/s. What is the velocity in the smaller pipe? Solution Answer: Continuity equation states that : A1V1 = A2V2 therefore A1 = pi* r2 while radius of larger pipe = 2r therefore A2 = pi* (2r)2 = 4*pi* r2 = 4*A1 therefore putting in equation A1V1 = 4*A1*4 = > V1 = 16m/s.