Wow, you ppl really don't understand anything.
No, that would still be you.
Water. Water applies motion to a water wheel.
And where does this motion come from?
A potential different due to an elevation difference and gravity.
No gravity, no reason for the water to move, no reason for it to spin the wheel.
because water weighs more than empty air
You mean because gravity is acting on the water?
But what about if you don't have gravity.
Where is this force coming from to spin the wheel?
Well before anyone believed in gravity
Just like in the other thread, you don't need to know what gravity is to be affected by it, or make things which rely upon it.
You can observe things falling and make a contraption based upon that, without understanding why they fall.
But forces are not the only things that move things.
What other than forces move things?
Be sure to explain how, including how they provide it directionality.
If I open a dam, and water rushes in at gallon after gallon, and this pushes the dam's wheels
The question is why does it rush in?
If not for gravity, it should be perfectly fine staying where it is.
So what causes the water to rush in, to get to a lower point?
If a bunch of people slam into a door to force it open, is it the force of gravity?
No, but that is nothing like water.
People can walk around in any direction (along the ground) by exerting a force on the ground.
Water is not sentient and can't just decide to push itself around.