.....at : www.geocities.ws/iacob_alex/Some_Drafts/untitled016.JPG (http://www.geocities.ws/iacob_alex/Some_Drafts/untitled016.JPG)
We can use a first class lever with a variable arm due to a tilting/inclined plane motion in two points : here one does not lift the CoM ,this is rotated by 90 degrees , almost in horizontal position.
Simply , we play a lever and a hinge.
Al_ex