I'm currently taking a calculus 2 course and I don't really understand the differences between the disk method for finding the soild of revolution and the washer and shells methods. I gather that the shells method is easier when you are rotatating around the y axis and disk is better when rotating around the x axis. Washers seems to be good for when there will be a hole in the object that you are rotating. My problem is that I don't really know how to use these methods and have been stuck for hours now trying to apply them.
Thanks a lot.