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course PHY 232
4/14 3:42 pm
Brief Bottle Experiment 3d
The setup is the same as for experiment 3 c, except that this time the vertical tube won't all be vertical.
Let the vertical tube flop around any way it will, but have the end of the tube 40 cm above the water in the bottle.
Take data to determine the change in the length of the air column in the pressure tube, relative the the original atmospheric-pressure length, as you heat the system until water begins to flow slowly out of the tube. Allow water to flow slowly out as you make a measurement.
Report you data and how you measured it, then answer the question: What is the length of the air column, as a percent of its atmospheric-pressure length?
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I was able to clip the tube at 40 cm and measure the column length. My initial column length was 25 cm and I wrote down 40-38.5 for the air column length at 40 cm. Unfortunately I'm not sure if that's exactly right because it seems awfully high and I don't' remember it being that high but it could be. What's going on though is that the net change in P is only the 40 cm, which is a small portion of the total length used in other measurements so it might be that it was actually 38.4 cm from 25. That gives a 54% increase over the P_atm length.
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Repeat, but this time have the middle of the tube at least 60 cm above the water level in the bottle. The end will still be at the 40 cm height. Adjust the flow of the tap so that no air enters the tube from either end during your measurement of the pressure tube.
Report you data and how you measured it, then answer the question: What is the length of the air column, as a percent of its atmospheric-pressure length?
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My recording this time wasn't any better as I wrote 25.5, which may be correct but I'm not certain and that make me very uncertain of what's happening since the water goes to 60 but comes back to 40 and that suggests to me that net change is still just 40 cm but that pressure tube length seems to say that P hasn't changed nearly as much as it did before. If the 60 cm was affecting P I'm not sure how and I would expect P to increase rather than decrease. Anyway that 25.5 to 25 is a 2% increase over P_atm length.
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@& I would expect the pressure to continue to increase linearly with column height until reaching the 60 cm height, at which time it would decrease to the same value it had at the 40 cm height. Might be challenging to measure, though.*@