Re: vibration vs. oscillation

[Carl Mungan <mungan@USNA.EDU>]

>  > Suppose a ball rolls without slipping down a rough inclined plane. I
> >  am guessing you would like to call this an example of conservation of
> >  mechanical energy: gravitational PE is converted into bulk
> >  translational and rotational energy since static friction does no
> >  work. This argument can be found in many intro books, but IMHO it's
> >  nonsense.
> >
> >  By the same logic, if I start from rest and accelerate up to walking
> >  speed without slipping on a level floor, my mechanical energy has
> >  been conserved!!
>
> Can one apply the "same logic" to the non-articulated ball and the
> articulated human body?
>
> Brian McInnes

Keep in mind that there are different opinions and methods for
treating these kinds of situations.

However, in my view the answer is definitely yes. In both the ball
and the human cases, there is an exchange between energy relative to
the COM (internal energy) and energy of the COM (what I prefer to
call mechanical energy, but I recognize that the nomenclature is
itself part of the trouble). We simply need equations to treat both
of these energies (and we have them). Carl
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5040
mailto:mungan@usna.edu       http://usna.edu/Users/physics/mungan/