1. The problem statement, all variables and given/known data A test tube of length [itex] l=16 cm[/itex] is completely immersed with its uncovered end in a mercury vase. The initial pressure of the air is the atmospherical pressure, and its initial temperature is [itex] t=27 degrees Celsius[/itex] so that the column of air has a height [itex] h= 40 mm[/itex]. We extract the eprubete so that its uncovered remains in contact with the mercury. How much do we have too cool off the temperature so that the height of the column of air stays the same? To better ilustrate the problem I drew a picture. 2. Relevant equations Well, if the height of the column of air remains the same we have an izocore transformation. 3. The attempt at a solution I belive that the solution of this problem is found writing and solving the equation of the izocore transformation. But I don't know how to find the initial and the final pressure.