We have two (narrow) capillary tubes T1, and T2 . Their lengths are l1 and l2 and radii of cross-sections arc r1, and r2 respectively. The rate of flow of water under a pressure difference P through tube T1, is 8 cm3/s. If l1 =2 l2 and r1= r2 , what will be the rate of flow when the two tubes are connected in series and pressure difference across the combination is same (P) as before?