Re: [Phys-L] angular momentum - error

[brian whatcott <betwys1@sbcglobal.net>]

I would like to withdraw this erroneous comment.

Brian Whatcott   Altus OK

On 7/21/2014 9:06 PM, brian whatcott wrote:
> It would be more reasonable to assert (in my opinion) that for 
> Robert's conditions,
> angular momentum is only conserved about an origin at (-inf,0)
>
> Brian Whatcott     Altus OK        Indianian Territory.
>
> On 7/21/2014 1:04 PM, treborsci@verizon.net wrote:
> > Consider the motion of a ball, free of all forces, to be the constant 
> > velocity path:  x=a (a constant), and y= vt (v is its constant speed).
> > Its angular momentum about the origin (0,0) is simply m*a*v, a 
> > constant in time.  In the same way, Its angular momentum about any 
> > fixed point is a constant in time .
> >
> >
> > Bob Sciamanda
> > Physics, Edinboro Univ of PA (Em)
> > treborsci@verizon.net
> > www.sciamanda.com
> > -----Original Message----- From: Paul Lulai
> > Sent: Monday, July 21, 2014 1:36 PM
> > To: Phys-L@Phys-L.org
> > Subject: [Phys-L] angular momentum
> >
> > Hello.
> > I am finding I have some questions about conservation of angular 
> > momentum that I hadn't considered in the past.  If I am investigating 
> > the angular momentum of a soccer ball about a point, is angular 
> > momentum only conserved if the ball is orbiting about the center of a 
> > circular path or a foci of an ellipse?  Certainly a ball traveling 
> > directly west across a field does not have its angular momentum 
> > conserved.
> > I am completely excluding the idea of impulse, torques, and isolated 
> > systems at this point.  I just found I haven't thought about this 
> > aspect before.
> > Thanks for your thoughts.
> > Paul.
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