I just read that, with respect to a stationary tiny cube, suspended in a fluid, that has a negligible weight and dimensions:
Pressure is the same in every direction in a fluid at a given depth, if it weren't the fluid would start to move.
This made sense to me the first time, but then I realised that the condition for the fluid not to move is that the net force is zero. However, the net force being zero doesn't necessarily require that forces in all directions are equal, just that two forces pointing in opposing directions are equal?
So say, the vertical forces on a cube, pointing up and down, are 1N each, but then all the other forces pointing towards the sides of the cube, may as well be 10N each, and yet all the forces would cancel each other out, resulting in a net force of zero.
Am I missing something here?