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Thermal expansion (easy)

  1. Nov 18, 2013 #1
    1. The problem statement, all variables and given/known data

    A 61.00m long steel measuring tape is calibrated for use at 20.0∘C. How long is this tape under the following conditions:

    a hot day with 38∘C?
    Express your answer using four decimal places and include the appropriate units.
    i've been losing my mind over this, i swear i'm doing it correctly.

    2. Relevant equations

    ΔL/L=αΔT



    3. The attempt at a solution



    (38-20)=18°C

    (61m)(1.2*10-5)(18)= .01317m

    Mastering physics keeps telling me that I'm inncorrrect , I swear i'm doing it how the book wants me to do it.
     
  2. jcsd
  3. Nov 18, 2013 #2

    TSny

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    Homework Helper
    Gold Member

    Is this the length of the tape or the change in the length of the tape?
     
  4. Nov 18, 2013 #3
    it is the change in L
     
    Last edited: Nov 18, 2013
  5. Nov 18, 2013 #4

    gneill

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    Staff: Mentor

    Does it make sense that a 61 meter long steel tape shrunk to about 1.3 cm in length?
     
  6. Nov 18, 2013 #5
    obviously not.
     
  7. Nov 18, 2013 #6

    gneill

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    Staff: Mentor

    So. What is it that your formula is giving you?
     
  8. Nov 18, 2013 #7
    the ammount the metal is changing in length. Silly me, i didn't add it together
     
  9. Nov 18, 2013 #8

    gneill

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    Staff: Mentor

    Huzzah! :smile:
     
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