# Modelling a cylinder [closed]

I am fairly new to Mathematica.

I am trying to model an ideal cylinder of uniform density of radius R (any arbitrary value) which has a cylinder of radius R/2 missing from it. The resulting solid is rolling in a straight line. The centre of mass is calculated to be R/6 from the point equidistance to the circumference of the larger circle.

How do I go about doing this? And how would I be able to show a graph of angular rotation between the line perpendicular to the x-axis and the line of symmetry of this system?

## closed as unclear what you're asking by m_goldberg, LCarvalho, Alex Trounev, MarcoB, bbgodfreyJun 23 at 2:33

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• I don't suppose this is a homework question...is it? You'll usually get more 'bites' if you also post code you tried yourself...and then show us where your attempt failed...but this is a fairly standard mechanics question, with even an equation of motion with an analytical solution...finding the equation and looking at the docuemntation for DSolve will get you pretty far. – morbo Jun 12 at 21:46
• A well-labeled diagram of the system would be helpful. – m_goldberg Jun 13 at 2:29

## 1 Answer

Here's how you begin:

    RegionPlot3D[
y^2 + z^2 < 4 &&
-2 < x < 2 &&
y^2 + (z - .5)^2 > .5,
{x, -3, 3},
{y, -3, 3},
{z, -3, 3},
PlotPoints -> 100,
PlotStyle -> Opacity[0.5]]