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Homework Help: Thermal Expansion

  1. Jan 22, 2008 #1
    1. The problem statement, all variables and given/known data

    A hollow glass block is floating in a container of methyl alcohol. Initially, everything is at a temperature of 20 degrees C, and just 7% of the block is above the suface of the alcohol. If you heat the container (gently and evenly- so that everything warms up together), at what temperature will the block sink to the bottom?

    2. Relevant equations

    So far, I think I need these:

    V = V initial (1+Beta x change in Temp)

    Beta = Coefficient of Thermal expansion (volume)

    Buoyant force = rho x V x g (but I am not given the density of methyl alcohol in my book)

    Coef for Therm Exp. for Methyl alcohol = 1200 x 10^-6

    3. The attempt at a solution

    I am pretty sure I will use the first equation, I just don't know how yet.... I don't know any volumes,and I don't have any dimensions to get there, so I don't know how to begin. The 93% submerged tidbit has got to be useful, but I don't see how to use it :( Something to do with buoyant force....?

    Thank you ahead of time for any help!!!
    Last edited: Jan 22, 2008
  2. jcsd
  3. Jan 23, 2008 #2


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    Staff Emeritus
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    Gold Member

    The buoyant force depends on the density of a substance which is inversely proportional to its volume. You know the buoyant force must support the weight of the sphere as well.
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