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course Phy 232
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?
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The percent seems to change around 8%. The air column gets shorter.
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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?
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The volume of the air column would decrease. This would decrease by a similar amount.
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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?
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The number of air molecules would stay the same but it has more pressure on them.
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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?
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The mass of the air column would stay the same, but would be more dense.
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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?
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The pressure in the air colum would increase by around 10%.
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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?
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The pressure in the bottle would increase. However, the percent would be less based on its larger quantity.
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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?
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The forces will be equal and opposite on eachother.
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Which do you think is greater, the pressure in the bottle or the pressure in the air column?
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The pressures are going to be equal when the bottle is in the squezzed position.This is shown because the water moves throughout the tube to equalize the pressures.
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Measure the length of the air column.
What is the length of the air column?
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9.4 inches
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How far would the water plug have to move to make the air column 10% shorter?
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.94 inches
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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?
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7
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?
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1.3%
5.4%
12%
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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:
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With the hot and cold water, I achieved roughly .6 below and .75 inches above the original length.
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&#Your work looks very good. Let me know if you have any questions. &#