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Heat resistance

  • Thread starter yecko
  • Start date
  • #1
yecko
Gold Member
257
6

Homework Statement


upload_2018-9-9_16-49-24.png

solution:
upload_2018-9-9_16-49-41.png


Homework Equations


upload_2018-9-9_16-50-3.png


The Attempt at a Solution


I thought this question should use :
upload_2018-9-9_16-50-30.png
, but the solution manual used
upload_2018-9-9_16-50-47.png
instead, which 1/2 is missing... may I know what the 1/2 account for and why doesn't we need to multiply the equation by 1/2 ?
thank you
 

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Answers and Replies

  • #2
stockzahn
Homework Helper
Gold Member
498
136

The Attempt at a Solution


I thought this question should use :View attachment 230458, but the solution manual usedView attachment 230459 instead, which 1/2 is missing... may I know what the 1/2 account for and why doesn't we need to multiply the equation by 1/2 ?
Since the the parts ##A## and ##B## of the pipe are only "half-pipes", their surfaces are halved resulting in a doubled thermal resistance (and the ##2## in the denominateor vanishes).
 

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