I'm learning how use this program. And I have problem with how graph the solid of revolution.Here i write one exercise.
y=2-1/2x, y=0,x=1,x=2; about the x-axis.
This is the graph also the volume 
x=1 and x=2 limited the size of the graph and I don't know how do that in Wolfram Mathematica. The steps i think are: RevolutionPlot3d [2-1/2x,{x,0,4},{y,0,4}] ....


RevolutionPlot3D[2 - 1/2 x, {x, 1, 2}]– Dr. belisarius Aug 23 '14 at 01:51