15.4: Shell Analogy for Cylindrical Transformations When r and z are theta Independent
Explanation
The animation explains the space for . This shape is z-simple. Each r- infinitesimal ribbon, in -plane, forms an infinitesimal rectangular solid in -space that transforms to a shell in -space. In these cases, it is easier to investigate -plane and set up the integral there. That is why, we can move to either end of integral since a full rotation is done independently from the other variables.