Quandaries
and Queries 

Hello there, Problem:
Thanks! Kathy 

Hi Kathy, This is the diagram that I see of a cross section of
the napkin ring. (Actually I would describe it as a wooden bead.) To find the volume of the napkin ring use cylindrical shells and revolve the shaded region around the Yaxis. The limits are r <= x <= R. From the diagram you can see that Pythagoras' Theorem gives 

