can water falling under gravity create suction force and if so, how much force..if i put a huge strong tank on top of a hill and on top there is a tap connected to a huge body, then i put a another pipe on the bottom of the tank to empty..assuming that the tank n piping is water/air tight such that the only opening are at the pipe in the large water body like sea/lake and the other at the emptying point...i want to fill the system completely and then i empty..can i create a perpetual suction??
I think you are asking two questions.
First : Can falling water create suction? The answer is Yes, but the effect is quite weak. It makes use of the siphon effect and is limited by atmospheric pressure, so the maximum column of water you could lift is about 10m.
Second : Is it is possible to use this effect to create a perpetual motion device, or perhaps create a source of unlimited free energy? The indisputable answer is No. There are many websites which explain why such devices are impossible.