Air at 1 atm and 25C [v = 1.562x10 m2/s] flows in a 7-cm-diameter cast iron pipe at a velocity of 8 m/s. The roughness of the pipe is 0.3 mm. What is the head loss for a pipe length of 30 m? Use the Colebrook equation if 1- needed. a) 20.5 m b) 8.9 m 44.3 m 12.9 m 28.2 m Bo brak