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Homework Help: Another thermal expansion problem

  1. Nov 27, 2011 #1
    1. The problem statement, all variables and given/known data

    A vertical glass tube of length L = 1.2800000 is half-filled with a liquid at 20.0000* C. How much will the height of the liquid column change when the tube is heated to 30.0000*C?

    Glass linear expansion co = 1e-5/K
    Liquid volume expansion co = 4e-5/K

    2. Relevant equations

    3. The attempt at a solution

    I don't understand why the length of the tube matters other than as giving me the initial height of the liquid. Shouldn't I be given the radius of the tube instead? How far the length of the tube grows has absolutely no effect on how much the height of the liquid changes, but the space within the tube does..
  2. jcsd
  3. Nov 28, 2011 #2
    The circumference of the tube will change. Hope this helps
  4. Nov 28, 2011 #3
    The length of the tube doesn't matter nor does its radius (cancels out). It looks like you will need to calculate the Δ length the tube and liquid by ΔV/ΔA for each independently. Remember that γ=2α and β=3α. I am guessing that ΔV/ΔA for liquid will be greater than ΔV/ΔA for the tube.
  5. Nov 28, 2011 #4
    I got ΔL = 0.14mm. Do you have an answer?
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