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course Phy 202
2/19 11 pm
Brief Bottle Experiment 1A: Basic concepts of N, P, V, TIt is assumed that you have read through the file Physics_II_Initial_Bottlecap-and-tube_Experiments.htm, which will familiarize you with the bottlecap and tube and some of their uses.
The bottlecap can be screwed onto a typical soft-drink bottle. It probably won't work on a bottle which isn't designed for the higher pressure of a carbonated drink, such as a water bottle or some tea bottles. A larger bottle is preferable, but any size will work adequately. A clear bottle is preferable to a colored bottle since you're going to sometimes want to see what's happening inside the bottle, and a darkly colored bottle won't allow this.
Screw the bottlecap onto a bottle and squeeze the bottle. It should be no surprise that if the tube isn't capped, this will force air out of the tube.
Comparing the state of the bottle before and after you squeeze:
Does the amount of air in the bottle increase or decrease?
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decreases as you squeeze, then increases back to normal amount after you release
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Does the volume of air enclosed in the bottle increase or decrease?
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the volume decreases as you squeeze then increases as you let go
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Does the pressure in the bottle increase or decrease?
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the pressure increases as your squeezing and decreases as you release
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The pressure does increase and stays a bit higher than atmospheric pressure while air continues to escape. Air escapes until the pressure inside equalizes with atmospheric.
Then when you release air pressure inside decreases, so air is force inward by atmospheric pressure, and this continues until pressures again equalize.
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Does the temperature of the air in the bottle increase or decrease?
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proportional to pressure so if the pressure goes up while squeezing the bottle the the temp. decreases and vice versa
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If the number of air particles and the volume both stayed the same the the temperature would be proportional to the pressure. However that isn't the case here. Temperature won't change significantly as a result of the squeeze.
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Be sure you have explained all your answers.
Now cap the end of the tube and give the bottle a good squeeze, without straining yourself.
Comparing the state of the bottle before and after you squeeze:
Does the amount of air in the system increase or decrease?
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the air in the system remains the same
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Does the volume of air enclosed in the system increase or decrease?
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the volume stays the same in the system as well
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If you squeeze the volume will decrease.
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Does the pressure in the system increase or decrease?
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the pressure increases slightly because of the small amount of air in the system when squeezed
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Pressure increases due to decreased volume. Temperature changes are insignificant.
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Does the temperature of the air in the system increase or decrease?
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as stated earlier temp. is proportional to pressure so it decreases slightly as you squeeze due to the small amount of air in the system
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