Re: [Phys-l] Significant figures -- again

[chuck britton <cvbritton@mac.com>]

Don't confuse counting with measuring.

There really are 144 sq inches in a square foot and twelve eggs in a 
dozen even tho they may be laid out as 6 x 2.
.
At 4:15 PM +0000 3/7/12, Philip Keller wrote:
>  > bounces@carnot.physics.buffalo.edu] On Behalf Of Richard L. Bowman
> >  One should not apply it to intermediate results on the way to a final
> >  answer. This is also true forr the more formal derivative method. One should
> >  look at the whole procedure not just at parts of it.
>
> Yes, I agree.  But that is still strange!  If every day, I throw 
> some pennies in a jar, I can keep track of the current total by 
> adding the new amount to the previous day's total.  No one will 
> suggest that to get the right answer I have to re-add the daily 
> contributions.  But if I have that 12000 lb  bus and then over 50 
> days 50 passengers get on the bus, one each day, then at the end of 
> each day I find that the weight has not changed (according to the 
> rules of sig fig addition). But if I add up the passenger weights 
> first and then add, I get the more reasonable result.  So this time, 
> I can't just add the mass of the new passenger to the previous 
> running total.
>
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