1. The problem statement, all variables and given/known data Water flows through a tapered tube. At one end of the tube, where the diameter is 20 mm, water flows in at a rate of 1.0 liter / s. At the other end, where the water flows out, the diameter is 15 mm. How large is the flow at that end? 2. Relevant equations No equations needed. 3. The attempt at a solution What I am trying to understand in this question is if the flow rate is dependent on the cross-sectional area or not. With these kind of questions I always find it interesting to study extreme values. If I imagine a tube where one side has a very large cross-sectional area at one end while at the other end, the cross-sectional area is infinitesimal. Will the flow rate be the same? It sounds likely tough the pressure(F/A) will increase due to a lower cross-sectional area.