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course Phy 232
2/5 1015Brief Bottle Experiment 1A: Basic concepts of N, P, V, T
It 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?
Since we don't have liquid in the bottle, the amount of air will decrease as it's forced out of the tube.
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Does the volume of air enclosed in the bottle increase or decrease?
The volume will decrease proportionally.
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Does the pressure in the bottle increase or decrease?
No. Since the system is open, the pressure will remain constant.
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Does the temperature of the air in the bottle increase or decrease?
There will be a negligible increase in temperature due to the heat from my hands.
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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?
It stays the same.
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Does the volume of air enclosed in the system increase or decrease?
The volume dereases.
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Does the pressure in the system increase or decrease?
The pressure increases.
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Does the temperature of the air in the system increase or decrease?
We postulate that the temperature increases slightly.
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Independently from the heat in your hands, the temperature will increase due to the decreasing volume. Positive work is done on the system, so the system does negative work, and the internal energy must therefore increase. The mechanism: The walls of the container are moving torward to molecules that collide with it, speeding them up in the collision.
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&#Your work looks good. See my notes. Let me know if you have any questions. &#