I've read in Wikipedia that:
"if a liquid is contained in a cylindrical vessel and is rotating around a vertical axis coinciding with the axis of the cylinder, the free surface will assume a parabolic surface of revolution known as a paraboloid. The free surface at each point is at a right angle to the force acting at it, which is the resultant of the force of gravity and the centrifugal force from the motion of each point in a circle."
Why does it form a paraboloid? My particular difficulty is that all points are supposed to be acted upon same forces so I don't understand the reason they are rotating at circles having different distances from the axis of rotation.
