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course phy 201
Atwood System: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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5seconds
2seconds
The question asked for your counts, and your counts wouldn't have been in seconds.
However these results are in the range of most observations of this system.
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`qx002. What were the two accelerations?
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4cm/s
25cm/s
good, but the units were cm/s^2
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`qx003. Why did the systems accelerate?
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Because of the weight of the paper clips out weighed the weight on the other end that did not have the weight.
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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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Fnet=MA
Fnet=(30g)(4cm/s)
Fnet=120g/cm/s
Fnet=MA
Fnet=(31g)25cm/s)
Fnet=775g/cm/s
There were six large clips in the system, not three. So masses would be 60 g and 61 g.
units of acceleration are cm/s^2 so the force would be in 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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Net Force=120
Net Force 775
For each trial you have 30 g on one side and 31 g on the other. For the first trial the two forces had magnitudes 30 g * 4 cm/s^2 and 31 g * 4 cm/s^2. on the second trial the magnitudes of the forces were 30 g * 25 cm/s^2 and 31 g * 25 cm/s^2.
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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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Less than a 10 to 1
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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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Fnet=MmA
you don't multiply masses
on the two sides the forces would be (6M + m) a and 6 M a
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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 this would be sufficient to explain the acceleration when the 3 large clips.
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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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Well when I got the system to balance the I added the magnet It took 4 dominos and I placed the small magnet on the domino and it moved the system but the system never actually returned back to the orginal equilabrium it moved it down ward to the magnet. So the magnet moved the equibuim.
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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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I did not measure this but when I added the magnet it was noticeable. I would have to say a couple of mm.
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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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To either increase or decrease the length the suspended paper clip. If you want to increase the length bring it away from the system to decrease the length bring it closer to system.
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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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I would say by at least 75%, the magnet changed the whole direction of system and changed the equilbium, until moving the magnet did the system go back to normal and then it still did not balance correctly.
&#Be sure to see my note(s), inserted at various places in this document, and let me know if you have questions. &#
&#Good responses. Let me know if you have questions. &#
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