Re: [Phys-l] bound vectors ... or not

[John Mallinckrodt <ajm@csupomona.edu>]

Mike Edmiston wrote:

> John Mallinckrodt wrote... "If you want to get the physics right,  
> you have to know exactly where
> the force is applied, not merely the line along which it is applied."
>
> I ask... are you sure?

Yes.

Just for example, pulling an object *always* produces a different  
result than pushing it.  You might not care about the difference, but  
that's another matter.

> Just because we physicists do not typically view a force as having  
> a location in space, that does not mean all professions view it  
> that way.  Engineers appear to view a force as having a line of  
> action, and I believe that has given me some physics insight I did  
> not possess prior to this thread.

That surprises me a little, but fine.  We can teach students, as I  
have always done and, frankly, thought most people did, about the  
importance of the "line of action" and how it can simplify the  
analysis of problems involving torques.  The "line of action" is a  
prominent enough feature to appear in the indexes of the first two  
intro physics texts I opened.

Nevertheless, I still fail to see any advantage to inventing a new  
category of vector.  I can't imagine how one would unerringly  
distinguish between "bound" and "free" vectors nor can I imagine any  
benefits to being able to do so.

John Mallinckrodt
Cal Poly Pomona