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Homework Help: Heat released by mercury while filling up the tube

  1. Apr 27, 2012 #1
    1. I have an airless tube connected to a pot full of mercury. After opening the tap, marked as K, mercury grew up by height h and mass m. How much heat was released in this situation?

    P.S. I do not have any exact numbers or sizes...only variables...

    2. Relevant equations

    3. All i did yet, is that i tried to think about the first law of thermodynamics, but what i get here is that i do not have the capacity V when calcutating the work. I also think I should use A=mgh, because i have m and h

    So could anybody give me any idea where should I start?
    http://img43.imageshack.us/img43/721/kraniukas.png [Broken]
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Apr 28, 2012 #2
    The only thing I can think of is the heat generated due to shearing of the liquid. Here, with the liquid flowing in a conduit, the liquid in contact with the wall has zero velocity. As you move radially inward, the velocity reaches a maximum at the center of the tube. Therefore, there is shearing going on and a small amount of heat will be generated and there is a small temperature rise. Assuming the flow the mercury was at thermal equilibrium with its environment initially, the very slight heat build up will pass through the glass tube and enter the environment.
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