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course PHY 231
10/12/10 9:20am. I'm behind on my submissions and I'm getting caught up as much as I can today. First the labs and then the Queries.
Questions about lab`qx001. Most of you found that the period of motion for the balance when the large paperclip was suspended in water was less than that for the straightened small paperclip. What were the two periods, and what was the ratio of the two?
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I had a problem here because my counts were too slow to tell any real difference between the two periods. I have redone my count to be about twice as fast as before to get more accurate results but have not been able to revisit this yet. I actually made one of these at home just for fun and hopefully soon will get this done right. My intuition here wants to say the ratio is something like 1:3 in favor of the small clip.
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`qx002. Which system experiences the greater change in buoyant force when the clip goes a centimeter deeper.
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Clearly the larger clip as it displaces more water than the small one.
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`qx003. Give your best explanation why you would expect the system with the large suspended paperclip to have the shorter period.
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The buoyant force acts as a restorative force and since that force is greater the balance restores its equilibrium more quickly which in turn means smaller periods.
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`qx004. Speculate on whether the period of motion would remain constant through several cycles, if instead of a paperclip or wire the suspended object was a thin metal cone. What difference would it make if the cone was suspended from its apex as opposed to its base? What if instead of a cone the suspended object was a sphere? These are big open questions that can easily go beyond the scope of this course so don't spend an inordinate amount of time thinking about them, but do give the cone some thought. Hint: how would the buoyant force change with the depth to which the object is suspended in the water?
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With the cone orientation is going to matter as it will determine how much water the cone displaces since, clearly, the cone pushed in base first would displace more water than the apex. As for the sphere I'm not as sure but I know, obviously, orientation won't matter just depth of submersion. The period of motion for both of these would vary much greater depending on how much of the object is in the water. Since the dimensions for these vary more that the right cylinders of the clip the buoyant force will vary more.
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Looks good. I don't expect that the Atwood system will give you much trouble.
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