I am designing a system for an engineering project at school. It's essentially a clock to be powered by water turning a mechanical system of gears (not generating electricity). Imagine a rectangular basin full of water placed at some height above the ground. There is a hole in the bottom, allowing water to flow out due to the effects of gravity. This water free falls (either through a pipe, or just through air) and hits a "water wheel", causing it to turn. The water wheel, in turn, causes other gears to turn, which go through a series of reduction processes to slow the turning down. If I need the gears to be turning at a certain rate to make the clock accurate, how can I find the speed at which the water strikes against the water wheel? Assume flow through the hole/pipe is constant. Is there a certain equation or set of equations I should be using to find this? Would I use Bernoulli's equation? Please tell me if I left something unclear.