🚀 go-pugleaf

In article <1992Dec11.170337.22897@asl.dl.nec.com> terry@asl.dl.nec.com writes:
>   Sure -- in the absence of gravity, my 3-pronger will eventually flip over.
>
>   However, when I said that there "isn't enough stored energy in the system to
>   make it flip," I was referring to the energy needed to raise it out of the
>   metastable state, not the net energy gain:
>
>               Metastable   Energy Needed to     Stable
>               Levitation    Rotate 3-Prong       Final
>              Energy State  Around horiz axis     State
>
>                                   --                     
>                                 -    -                   
>                                -      -                  
>                               -        -                 
>                              -          -                
>                             -             -              
>                           -                -            
>                  -------                     -           
>                                                -         
>                                                  ------  
>
>        Peak_energy(theta) = f(arm_length) = ~ constant x arm_length
>
>   Would you agree that this diagram and the ballpark equation under it describe
>   the energetics of flipping my three-pronged device in gravity?

NO!

I would maintain that you had something like this before the arms:

  Initail      Trans.     Finial Stable 
  unstable     State         State
  state               

   ------------
               --
                 -
                  -
                   --------------  
           
            
Adding the arms changed this to:


  Initial      Transitional state     Finial Stable
  unstable                               State
  state

  --------------  
                ---------
                         -------
                                ------
                                      -------------

The arms do not add in any energy barriers.  The object rotates about its
center of mass, so energy is conserved.  The arms do increase the moment of
inertia, slowing down the flipping process.  If you slow this down enough,
maybe you can then use small air currents or something to stablize things. 

>  Any experiments yet?  It might make a nice paper if it actually works...

That is really the best way to prove or disprove if your setup is stable.
Afterall, your initial post wasn't really too clear, so I could have
mis-interpreted what you have in mind.


                                      Bill