Simple temperature conversion

  • Thread starter portofino
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  • #1
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Homework Statement



i feel rather stupid posting this, but i can't seem to figure it out:

increase a sample by 43.8 degrees celsius. if the sample is already 62.7 degrees fahrenheit, what is the temperature in degrees fahrenheit when the desired temperature increase has been achieved?

Homework Equations



Tf = (9/5)*Tc+32 where Tc is temperature in celsius and Tf is temperature in fahrenheit

The Attempt at a Solution



convert 43.8 celsius to fahrenheit:

Tf = (9/5)(43.8+32) = 110.84 fahr.

sum initial temp and converted temp:

Tfinal = 110.84 + 62.7 = 173.54 fahr.

i know that the answer is NOT 173.54 fahr because the "temperature change does not depend on the freezing point of water." what am i doing wrong?
 

Answers and Replies

  • #2
Kurdt
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What you need to find out is the change in Fahrenheit that corresponds to the change in Celsius. What you have worked out is simply the equivalent temp in Fahrenheit for a given temp in Celsius.
 
  • #3
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do you mean i do the difference between 173.54 - 62.7 = 110.84? isn't that the change fahrenheit?
 
  • #4
Kurdt
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No I mean you have a change in Celsius of 43.8 degrees. That is the difference between some final temperature and some initial temperature. You will have to work out Fahreheit for the initial and final and find the difference. It doesn't matter what numbers you choose as long as they differ by 43.8 degrees Celsius.
 
  • #5
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i am still confused. isn't 110.84 the fahrenheit temperature difference equivalent to 43.8 celsius?

so couldn't i chose 0 deg fahr. as the initial and 110.84 deg fahr. as the final temperatures?

what formula should i be using, is the one i listed in the original post the correct one?
 
  • #6
Kurdt
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No 110.84 is the Fahrenheit equivalent temperature as 43.8 Celsius not the equivalent temperature difference.

You could chose 0 degrees Celsius as the initial and 43.8 as the final, find the Fahrenheit equivalents and then find the equivalent Fahrenheit difference.
 
  • #7
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so 0 deg celsius = 32 fahr, 43.8 deg celsius = 110.84 fahr

so the fahrenheit difference is 110.84 - 32 = 78.84 fahr. thus the temp when the desired temp increase has been achieved is 62.7 + 78.84 = 141.54 fahrenheit

correct?
 
  • #8
Kurdt
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Looks good to me. :smile:
 
  • #9
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thanks, it was correct
 

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