@acer Thanks! 

@dharr That will work.  Thanks!

@C_R ok I see, I think. Since rolling body is massless there's no angular momentum ... ok that sounds wrong but seems right, at least for the object - the swinging pendulum would be providing angular momentum, wait I guess that would be torque? .. hard for me to envision a rotating object with zero momentum (unatural) but with mass 0 the math says it's zero p=m*ω and so momentum is zero.

I might be envisioning/confusing two different cases - a freely swinging pendulum on an axis inside a rotating disc and a fixed pendulum with a massless rod which is just a point mass some distance from the center of the mass on a disc.  I'll have to think more...

I edited one of my responses above, to say that a sign in the internal calculation of a solution may be wrong.  But it looks like a fix that C_R mentions is deleting all demultiplexers and loading new ones from the library.

@C_R  Does the animation in maplesim work correctly now?  Can you show the fixed animation?

So a similar thing ocurrs here with the ball bounce How to model a bouncing ball through event handling? - MaplePrimes

Could be related problems.

@OrangVahid It still seems that something is mishandled incorrectly within maplesim.  There is a similar issue that ocurs with a ball bouncing on a 3d terrain. 

@C_R I must say, your write up is an excellent addition using maplesim.  I must also say Maplesim is pretty awesome, although my use with it is very sporadic and liimited.

That's quite an in depth analysis.  Great job!

I asked a question like this about 6 years ago so here's some solutions others came up with in maple here's the link for others looking for more, https://www.mapleprimes.com/questions/225760-Spinning-T-Handle-In-Space

@C_R Did you fix the initial warnings and initialization problem?  What were they exactly?

Which MapleSim version are you using?  Looks like you made some progress, that wall at the 12.5 second mark is strange.  Probably some calculation that needs to be relaxed or something.  

**edit ** almost like a sign in an equation   a internally calculated solution is opposite of what it should be.  I think at 12.5 seconds if it rolled through that reflection it would look normal.  ... maybe not.  Just trying to think of ideas that might spur a "eureka" moment.  

@Ronan ok that makes sense.  Luckily there is that backup option.  Of course there is that query when you shut down a Maple session if you wish to save your work.  I think at that time a backup copy of the sheet should be made regardless of saving the file or not - perhaps that could be an option?

Ah, one thing I noticed.  I actually did save the file and discovered a dificiency in Maple.  A new file saved by Maple does not appear in the recent file list.

So this would be one good reason to leave the automatic saves on, especially if you haven't saved a worksheet yet. Saves a lot of work from being lost.

@Ronan Thank you.  That's it. 

So in Microsoft Word the option split window would perform like I would want a similar function to work in Maple.

@Scot Gould oh ok so you're talking about excel?

I'm using an ancient version of excel - Excel 2007, but 365 should have the same option.  Use the split icon. It splits the cells - ironically I haven't checked and don't even know if Microsoft Word can do that.  Although I've never used Microsoft Word enough to think I might need that option.