Re: Friction (STATIC)

[John Denker <jsd@MONMOUTH.COM>]

> At 11:11 PM -0400 10/17/00, Ludwik Kowalski
> mentioned:

> >  F_st =mu_st *
> > N 

Then at 08:50 AM 10/18/00 -0400, Chuck Britton wrote:

> Some observant student will note that the
> vector nature of this
> Equation is completely WRONG!
> (an equal sign that connects force vectors which are orthogonal to
> each other ! ! ! !)

Calm down.  Let's give Ludwik credit for writing an equation between
the magnitudes of vectors.  I don't see any boldface fonts, nor any
little arrows decorating the alleged vectors.

> If you use it as a Scalar Equation (without
> de-emphasizing that force
> is a vector!)

Talking about the magnitude of a vector doesn't make it any less of a
vector.

>  then you would be well advised to
> replace the = sign
> with the (more) correct < = (less than or equal
> to).

That is a valid point about the physics -- but people often just define
the LHS (F_st) to describe the "maximum static friction".