Re: [Phys-L] form of Newtons 2nd and 3rd laws

[Paul Nord <paul.nord@valpo.edu>]

On Jul 26, 2012, at 11:10 PM, John Denker wrote:

> > I've had engineers insist that it should be presented as:
> >
> > a = F/m
> >
> > (Some Engineers are very good at insisting)
>
> Gaaack.  We have seen physicists insist on the same thing, in this
> very forum.  It's related to not understanding the difference between
> equation and causation.
>  http://www.av8n.com/physics/causation.htm

A few physics textbooks do it this way.  You and I know that it makes no difference.  We can manipulate the algebra to solve for what we don't know in terms of what we do know.  For introductory physics, most problems involve using a force to move something.  The independent variable is force.  It's something we can change and manipulate.  The dependent variable is the result we can expect to observe - the mass begins to accelerate.

You probably never struggled with this concept.  For those students who do struggle, writing it in this form will help them get past this stage.

Paul