20 12 The math problem in Suzhou senior high school entrance examination is difficult.
Suppose a uniform cube is dug in the cylinder (the bottom area is EFGH, and the height of the cylinder is high), and it becomes a hollow shape similar to a constant pressure ring.
Compared with B, there will be a little more, so the gravity will be greater, and the pressure will be greater under the same bottom area (P- structural cylinder = P- solid).