Hi, I have this problem: I have a vertical tube 1 meter D, in the bottom end there is a nozzle with 0,5 m D. The tube is full of water. the tube lenght is 10 meters and the nozzle lenght is 2 meters. I need to calculate the power of this by this equation: W = Q * g * h * p where W is watt, Q is the volumetric flow rate, g is 9.81,h is the head and p is the density (1000 kg/m3 for the water. The issue is the velocity in the nozzle: for the Venturi effect, in the nozzle the velocity increases. So in the velocity Torricelli's equation: sqrt(2 * g * h) = v the h value changes in h = (v^2) / 2 * g that is greater then the real h value (12 meters). So in the power equations I use this second h value. Is it right? There is an explaination: https://en.wikipedia.org/wiki/Pelton_wheel#Power but I'm not understanding it.