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course phy 202
712 4/22
Brief Bottle Experiment 1bThe Air Column as a measure of Pressure
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Siphon a plug of water into the tube, seal the end of the tube to create an air column between the plug and the sealed end, and screw the cap back on. Give the bottle a moderate squeeze. Note that the tube should have come with a cap on the end, but the cap might have been left off; if so you can seal the end with your thumb; if the end is cut at a sharp angle you can easily cut it off square.
Does the air column get longer or shorter? By what percent do you estimate the length of the column changes?
It got longer it increased by about 50%
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Does the volume of the air column increase or decrease? By what percent do you estimate the volume of the column changes?
It increased with the air, since the air increased by about 50% I would assume that the volume would have a comparable increase
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Does the number of molecules in the air column increase, decrease or remain the same? By what percent do you estimate the number of molecules changes?
They remain the same, the molecules are just stretching out in the column. 0%
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Does the mass of the air in the air column increase or decrease? By what percent do you estimate the mass of the air in the column changes?
I think the mass remains the same because the total number of air molecules are the same just in an expanded form. 0%
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Does the pressure in the air column increase, decrease or remain the same? By what percent do you conjecture the pressure in the column changes?
The pressure is increasing because the same amount of air is in the column yet expanding and running out of room to increase I think it would increase by about 50% with the volume
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Does the pressure in the bottle increase, decrease or remain the same? By what percent do you conjecture the pressure in the bottle changes?
Increase 50%
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Good answers, except that if the end of the tube is really sealed very few, if any, people are capable of squeezing the bottle hard enough with a 'moderate squeeze' to compress the air column by 50%. Not many people could do that with their hardest 2-hand squeeze.
I suspect that the end of the tube might have been leaking a bit.
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When you hold the bottle in the squeezed position, with the water plug stationary, the pressure in the bottle results in a force on the plug which pushes it toward the capped end, while the pressure in the air column results in a force that pushes the plug away from that end. Which force do you think is the greater, or are they equal?
I think the force coming from the squeezed in is greater, but under these circumstances they may be closer to being the same. More pressure can potentially come from the bottle end because I would imagine that if squeezed hard enough the air will come out probably by blowing the plug off
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Which do you think is greater, the pressure in the bottle or the pressure in the air column?
Pressure in column tighter space less room to move
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Measure the length of the air column.
What is the length of the air column?
Approx. 5 cm
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How far would the water plug have to move to make the air column 10% shorter?
½ of a cm
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Squeeze the bottle so the air column becomes 10% shorter. It's up to you to figure out how to tell when it's 10% shorter. If you can't squeeze hard enough to achieve the 10% difference, then figure out what percent you can manage and note the percent in your answer.
On a 1-10 scale, with 10 the hardest squeeze of which you are capable without risking injury, how hard did you have to squeeze the bottle and what percent change did you achieve in the length of the air column?
4/10
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Now, using the same 1-10 scale, give the bottle squeezes of 2, 5 and 8. Estimate the percent changes in the length of the air column.
What were your percent changes in air column length?
2, 5%
5, 10%
8, 10% (slightly more than 10% but I wouldn’t say 15% or 20%
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Now by heating and/or cooling the bottle, what extremes in air column length can you achieve? Careful not to melt the bottle. It won't handle boiling water, and you shouldn't mess with water hot enough to scald you or cold enough to injure you (e.g., don't use dry ice, which in any case is too cold for the bottle, and certainly don't use liquid nitrogen).
Report your results:
Had difficulties heating and cooling. But it seemed to increase slightly with heating, but after heating I tried cooling and didn’t change much may have gotten smaller but remained nearly the same
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