Physics Help Forum Charle's Law

 Thermodynamics and Fluid Mechanics Thermodynamics and Fluid Mechanics Physics Help Forum

 Dec 8th 2012, 05:56 AM #1 Junior Member   Join Date: Dec 2012 Posts: 1 Charle's Law Hi There. I've got an assignment due Tuesday and typically the one part I was yet to do is the only one I'm having problems with We did the usual experiment with a bubble of air trapped under acid in a tube, changing the temperature and measuring volume etc. However the results weren't coming out as expected so the teacher got us to set up a second experiment. The main point of the experiment is to calculate absolute zero. Which I think I was doing correctly, it says to use the graph so I thought best way to do it is trace the line of best fit until it intercepts the axis, at 0 volume and read off the temperature. Also guess you could do it with a formula rearranged to make temp the subject. Either is acceptable I think, but the first experiment came out as about -60 c when I used the graph so way off the mark, therefore doesn't seem any point calculating it with those results. But that's fine, I can talk about possible reasons why it's so far off. Anyway to the point, the 2nd experiment I have no idea how it can be used to calculate absolute zero in the same way. Easiest is to post the diagram I did. To begin with the measuring cylinder was completely filled with water and hot water was added to the beaker with the test tube, so as the air expands it displaces the water in the cylinder. What I don't understand though is my initial volume was zero. Would I not have had to know the volume of the air in the test tube? could probably ignore that in the rubber tube but if I had the volume in the test tube I could of used this as the initial volume, then added the air in the cylinder to this. Am I missing something or is this impossible to do without the volume of air originally in the test tube? Thanks in advance for any help.

 Tags charle, law