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course Phy 242
April 19 around 9:15pm.
Brief Bottle Experiment 3b
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Set up one bottle with water in it, the vertical tube extending down into the water. The pressure tube should be set up as before. The vertical tube should extend upward at least a meter. A convenient way to raise the tube is to put the second cap loosely on another bottle about half full of water, which can then be set on a shelf (just be careful to keep that end of the vertical tube out of water, and that cap loose so the upper end of the tube remains at atmospheric pressure).
Seal the cap in the lower bottle so you can squeeze water into the vertical tube. Give the tube a squeeze of about 2 on your 1-10 'squeeze scale', and do whatever is necessary to get the data required to find the change in the vertical level of the water in the vertical tube, and accompanying percent change in the length of the air column.
Repeat for squeezes of 5 and 8 on your 'squeeze scale'.
Report what you measured, how you measured it and what your measurements were.
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Squeeze of 2: 28cm of water raised, about a 30% change in the length of the air column
Squeeze of 5: 90cm of water raised, about a 90% change in the length of the air column
Squeeze of 8: The entire vertical tube filled up and went into the bottle. The vertical tube is approx. 110cm (a little over 1 meter) so a 110% change in the length of the air column.
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Give a table of the heights to which water was raised vs. the length of the air column as a percent of its original length. Add a third column which gives the pressure resulting from each squeeze, as indicated by the height of the water in the vertical tube (that pressure should be given in Pascals).
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Heights (cm): 28cm, 90cm, 110cm
Length of air column (% of original length): 28%, 90%, 110%
Pressure (pascals): squeeze 2, 5, 8
How would I convert my “squeezes” to pascals?! I know pressure would be the force/surface area and 1 pascal = N/m^2.
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Based on your table, how many Pascals of pressure change should correspond to a 1% change in the length of the air column?
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@& The air column is the air in the end of the pressure tube. That tube is closed at the end. The air column is between a plug of water in that tube and the end of the tube.
You might be confusing the air column in the pressure tube with the open part of the vertical tube. You aren't going to have a 90% change in the length of the air column. You're pretty strong, but nobody strong enough to do that. It would require that the pressure in the bottle be raised to 10 atmospheres (enough to support a column 100 meters high).
The height of the water in your vertical tube will give you the pressure difference between the top of the water column and the bottom, in Pascals.*@
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