If one starts with a hoop and thinks about gradually filling in the
inside of the hoop with mass until it eventually looks like a disk, one
is certainly increasing the moment of intertia of the object. The effact
of the above transformation is to produce an object which will roll ever
faster down a given incline. I can show this easily mathematically but
is there an intuitive way of explaining why this happens? My students
understand the mathematics but seem to need a non mathematical argument
too.