Re: Sig Figures

["Carr, John" <carrj@METROLINK.NET>]

OK. I understand that.  If we were to follow the "rules" of significant
figures on a problem like adding vector

33.4 N at 55* to 359.23 newtons at 64.2*.

We get a value of 392.236703359 N at 63.419933*

The rules of significant figures states that you must use the least number of
significant figures. Do you use the given angle as significant or just the
vector magnitudes?  The book ignors the angle and the answer would be 392
newtons at 63.42*.  Are there any clear rules for handling angles in
significant figures (experimental or not)?

Ludwik Kowalski wrote:

> In my opinion significant figures are much more important
> while processing experimental data. In problems each of us
> is free to choose the level for rounding. I tell students that
> about 1% agreement with the textbook answer is OK (to know
> that the method chosen is likely to be good). We do not know
> how the rounding was done by the author. It is better to have
> too many digits (intermediate results) that not enough. In
> general the accuracy of a calculation depends on its purpose.
>
> In a problem 0.5 and 0.55 are always different , in a
> laboratory  report the difference between 0.50 and 0.55
> may or may not be significant.
> Ludwik Kowalski
>
> "Carr, John" wrote:
>
> > When your dealing with angles in problems like vector addition, or
> > inelastic collision at vector angles, how do you handle angles and
> > significant figures?  The book I use tends to keeps the angle to about 2
> > decimal places and does not follow significant figures of the data.
> > What are the guidelines for this?