Re: Sig Figures

[Leigh Palmer <palmer@SFU.CA>]

> 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?

Don't use significant figures. Instead you should insert uncertainties
in your inputs of the magnitude of uncertainties in your measurements.
Calculating your result two more times (using the extreme uncertainties)
will answer your question for you. Given that you probably use a digital
calculator this should not be an excessively arduous task.

"Significant figures" is a schoolboy rule; it isn't used in science
because it is so often wrong. I don't even teach it; I do carp about
*insignificant* figures, however.

Leigh