Some days ago I got confused trying to solve an exercise about fluid dynamics. Trying to simplify the problem here is a similar situation: I have a cistern connected to a tube containing a fluid as shown in the picture below. Assumming that the fluid is incompressible... I know from the law of continuity that every single point in the same area has to move with the same speed. However, Bernoulli's equation applied to the point B says that: P atm + rho*g*h = Patm + (1/2)*rho*V2 This implies that v = ( 2gh )1/2. but... in the point C it will be v = ( 2g(h+d) )1/2. That means that every single point has a different speed despite being in the same cross-sectional area. What's the right equation?. Am I doing something wrong?. Where's the mistake? PD: Both sides are open and it is supposed that the velocity of every "control volume" inside the cistern tends to zero.