Hi friends This isn't a homework poblem. However,I got this confusion when i was solving some problems. Consider fluid flowing out of a tank as shown in figure attached. Fluid moves out of pipe through a nozzle (generally used to accelerate the fluid). Now if we apply bernoulli's equation at point 1 and 2(shown in fig.) we find that fluid velocity comes out to be: V= (2gh)^1/2 (where h is height of tank above nozzle) which is independent of nozzle diametre. That means if i remove the nozzle and fluid flows through a pipe of constant cross section, then also velocity will be same. This can be checked by applying bernoulli's equation. But in general nozzle accelerates the fluid for same mass flow rate. How will you explain this?