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course phy 231
10/23 @ 11:45 a.m.
The Atwood system consists of the paperclips suspended over the pulley. A total of six large clips connected by a thread were suspended, three from each side of the pulley. The system was released and, one side being slightly more massive than the other due to inconsistencies in the masses of the clips, accelerated from rest, with one side descending and the other ascending. The system accelerated through 50 cm in a time interval between 4 and 6 seconds; everyone used their 8-count to more accurately estimate the interval. Then a small clip was attached to the side that had previously ascended. This side now descended and the system was observed to now descend is an interval that probably lasted between 1 and 2 seconds.If you weren't in class you can assume time intervals of 5 seconds and 1.5 seconds. Alternatively you can wait until tomorrow and observe the system yourself; the initial observation requires only a couple of minutes.
`qx001. What were your counts for the 50 cm descent of the Atwood system?
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4.5
1.8
seconds
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`qx002. What were the two accelerations?
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2.5
15.4
cm/s^2
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`qx003. Why did the systems accelerate?
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because the masses on each side weren't equal, thus causing the larger mass to have the greater force pulling down, so that force pulled the other one in the opposite direction.
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`qx004. Suppose the large paperclips all had mass 10 grams, the small clip a mass of 1 gram. What then was the net force accelerating the system on the first trial, and what was the net force on the second?
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150
939.4
g cm/s^2
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.. if uncertainty +-1%
`qx005. Given the masses assumed in the preceding, what is the force acting on each side of the system? What therefore is the net force on the system?
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75.75 on right side. 74.25 on left side.
With the small paperclip added. 466 on right side, and 472.78 on left side( side with the small clip added.)
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`qx006. Based on your counts and the resulting accelerations, do you think the ratio of the masses of the large to small paperclips is greater than, or less than, the 10-to-1 ratio assumed in the preceding two questions?
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the 10-1 ratio makes sense. The with the 1 percent error taking acount of, then the above numbers seem to make sense. The system with the just the 6 clips accelerated one way, and then adding the 1 small clip to the lighter end DOES make that side generate a larger force through the calculations.
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`qx007. If the mass of each larger clip is M and the mass of a smaller clip is m, what would be the expressions for the net force accelerating the system? What would be the expression for the acceleration of the system?
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(6M+m)(15.4)=F ( accleration in the counterclockwise direction)
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`qx008. If the mass of the each of the larger clips is considered accurate to within +-1%:, would this be sufficient to explain the acceleration observed when 3 large clips were hung from each side?
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yes, that would mean that the side accelerating downward would have .6 grams more in mass, so the acceleration in that direction makes sense then.
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... sample the accelerations for random divisions of the six large clips ... predict what the distribution of masses would look like ...
Magnet and Balance
Everyone was given a small magnet and asked to achieve a state where the balance was in an equilibrium position significantly different from that observed without the magnet. It was suggested that the length of the suspended clip beneath the surface of the water should differ by at least a centimeter.
... assuming 1 mm diam ...
`qx009. Describe in a few lines your efforts to achieve the desired result. What worked, what didn't, what difficulties presented themselves, etc.?
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I tried to position the magnet to balance the system but I couldn't. If I tapped the balance to move it a little., it wouldn't return the the previous position. It would stay at another position.
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`qx010. How much difference was there in the length of clip suspended in the water? If you didn't actually measure this, give a reasonable estimate.
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maybe 2 or 3 cm.
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`qx011. How did you adjust the magnet? If you wanted to quickly increase or decrease the length of the suspended paper clip beneath the surface by 1 millimeter, using only what you had in front of you during the experiment, how would you go about it?
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I would move the magnet a little over
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`qx012. Assuming the diameter of the suspended clip to be 1 millimeter, by how much did the buoyant force on the suspended clip change? How much force do you therefore infer the magnet exerted? If you have accurate measurements, then use them. Otherwise use estimates of the positions of various components as a basis for your responses.
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the buoyant force close to doubled. But I don't think that force had a significant impact.
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&#Good responses. Let me know if you have questions. &#
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