Hello!

I'm a student from a German school and I am currently writing a paper on rotational bodies (if this is the right word for it in English). As a rotational body I took a simplified chess piece, the tower, and described it also in the respective areas by functions. Now I intended to bring all these functions into one diagram and later if possible show a rotation as animation or just the figure at the end. But there are two problems:

1. I have found out how to bring several functions into a diagram and how to limit this diagram, but I want to limit the functions themselves, because they follow each other and do not occur at the same x-values. An simplified example:

Plot3D[{-0.065306 x^(2) + 0.228571 x + 16.75, -x + 20.25}, {x, 0, 
   4.4}, {y, 0, 20}]

I have the two functions:

1.-0.065306 x^(2) + 0.228571 x + 16.75

This one should go from x=0 to x=3.5

2.-x + 20.25

This one should go from x=3.5 to x=4.4

As you can see I limited x to 4.4 because that is the highest x value, but now both functions go from x=0 to x=4.4, which makes sense, but I want to limit each function individually.

2. Unfortunately I didn't quite understand how this should be possible with the rotation around the x-axis. I have read and informed but understood or have not found the right one.

Has it something to do with "RevolutionPlot3D"?

I hope you could read my English.

Many thanks in advance for your help!!

Mfg