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Calculating the coefficent of volume expansion of liquid?

  1. Feb 24, 2012 #1
    I can't seem to figure out this question.

    A Thermometer is filled with unknown liquid. It has a square bulb and a stem with cylinder shape. It is found that the volume of the liquid increased by 40% when the temperature changes by 15 Celsius.
    Calculate the coefficient of expansion of volume of the liquid and the radius of the stem if the liquid rises by 5 cm?
    Do I need to use the formula: ΔV = VβΔT

    Don't know how to tackle this question any help would be appreciated.
    Last edited: Feb 24, 2012
  2. jcsd
  3. Feb 25, 2012 #2
    :surprised WOW! I am stuck on exactly same question.
    Someone tried to help me with this..I thought I understand it all now but I am stuck again haha.
    This might make sense to you then you can help me.
    For 1st part the volume coefficient of expansionis the fractional increase in volume per unit rise in temperature. The % increase is given so change that to a fraction and divide by the rise in temperature (0.4/15 = 0.0267?? may be :S)
    For the 2nd part if you know the vol of the bulb, then you can work out the increase in the actual vol of the liquids because you know it increases by 40%. The tube is a cylinder and liquid will have a vol = area of cross section x length. You know the increase in volume and you know the length so work out the area of cross section and hencethe radius.
  4. Feb 27, 2012 #3


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    Staff: Mentor

    I think you explained that very well, SAFiiNA. And judging by the absence of any further query from Pinchie81, I'd conclude that you managed to answer his/her questions! :wink:
  5. Feb 27, 2012 #4
    Thank you! :) I finally managed to work it out myself.
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