Suppose that I have a hole which is just large enough in diameter to accommodate a particular cylindrical post, but insufficiently deep to fully submerge the post.
Now suppose that I wished to enlarge this hole using the protruding portion of the post as a lever. I start by wiggling the post back-and-forth very slightly, then I change directions and wiggle it some more. Now there is enough slack that I can begin to forcefully rotate the post, at first with a small diameter but progressing to larger diameters, so that I now have now produced a large cone-shaped hole.
I don’t know, but I think the hole will be the intersection of two cones that are overlapping a bit coaxially. That is, if you push the top of the pole to the right, you will cause the bottom to shift to the left, and it will pivot about some point. If the part of the pole sticking out is much longer than the part in the hole, and you are grabbing the exposed end, the pivot point will be mid depth in the hole. Only if the part sticking out is very short compared to the submerged part will the pivot point be near the bottom of the hole.
I’ve always called it “wallowing out” the hole. Same thing as when you need to make a hole with a drill, and don’t have the right size bit. The guy that I learned this term also said things were cattywompus when they weren’t straight, so take this one with a (southern) grain of salt.
ETA: Napier, not sure what you’re saying. The way I’m envisioning this, the pivot point is always going to be either the bottom of the hole, if the pole is embedded, or the top of the hole, if it’s not. Why would the length of the pole matter?