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Old Aug 31st 2018, 03:03 PM   #1
Sammy
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Temperature conversions

Hi guys,

I'm having trouble figuring out what the rules are for determining the right amount of significant figures in the final result of a temperature conversion. In the problems I did they didn't seem to follow the regular rules of sig figs, what am I missing?

Thanks!
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Old Sep 5th 2018, 12:31 AM   #2
Woody
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I am guessing that the problem was stated poorly
Significant figures are far too often not considered properly.
As a guess was the original temperature table given as nice round numbers,
expressed to just a small number of significant figures?
so perhaps 21, 22, 23 deg. C
and the result to several decimal places?
This perhaps indicates that the original table should have been expressed as,
21.000, 22.000, 23.000 (for example)
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Old Sep 5th 2018, 09:02 AM   #3
Sammy
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Originally Posted by Woody View Post
I am guessing that the problem was stated poorly
Significant figures are far too often not considered properly.
As a guess was the original temperature table given as nice round numbers,
expressed to just a small number of significant figures?
so perhaps 21, 22, 23 deg. C
and the result to several decimal places?
This perhaps indicates that the original table should have been expressed as,
21.000, 22.000, 23.000 (for example)
Pretty much...the results weren't all to several decimal places, but these were the questions and answers given by the book-

1) 32'F to 'C (freezing temp of water) = 0'C
2) 77K to 'F (temp of liquid nitrogen) = -321'F
3) -109'F to 'C (temp of dry ice) = -78.3'F
4) 98.6'F to K (body temp) = 310.2 K


I got all the numbers right but my SF's were off. Am I missing something?
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Old Sep 6th 2018, 01:15 AM   #4
Woody
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ok,
The whole point of the significant figures rules is to avoid indicating a higher degree of accuracy than is actually present.

You could argue that the problems have been expressed in a slightly lax way with respect to the significant figures "rules"

However, I think that they still satisfy the key issue,
which is avoiding indicating an inappropriate level of accuracy.

I think it is one of those situations where if you just follow the rules, without appreciating their proper purpose, one can loose sight of the appropriate answer.
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