Re: [Phys-l] formatting uncertainties

[Rick Tarara <rtarara@saintmarys.edu>]

----- Original Message ----- 
From: "John Denker" <jsd@av8n.com>
> > ... I suspect that the primary thing most instructors
> > are dealing with is students multiplying two values on their calculators 
> > and
> > then writing down every digit that appears.
>
> Is that a problem?  Why should that be a problem?  Tell me,
> please, who is harmed by those "extra" digits?  How does the
> cost of keeping "extra" digits compare to the cost of keeping
> too few digits?
It depends on what the student thinks she is communicating when she says 
(reading off the calculator) that the volume of the rectangular solid (H = 
5.67 cm, L = 3.25 cm, W = 4.11 cm--as measured in lab) is 75.737025 cm^3. 
This is a typical situation where significant figures (digits) are 
introduced and they work well enough for this.  They also work fairly well 
for most other intro level experiments.  Having 4 'guard' digits in the 
answer seems more confusing to me--does the student really understand the 
level of uncertainty in the answer?

Rick