course phy202
I am working as hard as I can to finish the assignments. But, I have a full time job with a engineering firm here in Grundy which is cutting into the time I need to complete the course. I can see from the start that this class is not designed for working individuals. I am currently this evenging knocking down coffee and do as much work as I can and will continue thru the weekend trying to get to the first test. This is actually the last class I need to graduate from ODU with a Civil Engineering & Construction Management degree so I hope you can understand my dismay. I just wanted you to know that I am doing my best to finish. If something happens and I cannot get to the last tests in time, is there some sort of extension into May that would be allowed? Hoping not to do that but wanted to ask. Also, I listed my company email on the form because the vccs email will not work half the time?
I think it will be possible for me to give Incompletes this semester according to my long-standing policy, with students who complete at least the half the course receiving the I grade. However there is a change coming in the policy for Incompletes, and if that change is in effect for this term it might not be possible to follow my previous policy.
I won't be able to check this out until early next week. Please repeat your question again at that time so I can give you a definitive answer.
I can post my answer to your access site.
However you need to give your VCCS email address when submitting forms. You can also include your work email, but within the body of the form rather than in the box which requests you email address. My policy on Incompletes is general information and has nothing to do with your performance or any other protected information, so I could send a copy of my reply to your work email.
• Which result is likely to be closer to the actual length of the pencil?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The original ruler.
• What factors do you have to consider in order to answer this question and how do they weigh into your final answer?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The error in adding a multiplication to the ruler adds chance of precision loss.
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Question: Answer the same questions as before, except assume that the triply-reduced ruler has no optical distortion, and that you also know the scale factor accurate to 4 significant figures.
• Which result is likely to be closer to the actual length of the pencil?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The original ruler.
• What factors do you have to consider in order to answer this question and how do they weigh into your final answer?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv Still, as before, the error in adding a multiplication to the ruler adds chance of precision loss.
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Question: Suppose you are to measure the length of a rubber band whose original length is around 10 cm, measuring once while the rubber band supports the weight of a small apple and again when it supports the weight of two small apples. You are asked to report as accurately as possible the difference in the two lengths, which is somewhere between 1 cm and 2 cm. You have available the singly-reduced copy and the triply-reduced copy, and your data from the optical distortion experiment.
• Which ruler will be likely to give you the more accurate difference in the lengths?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The single reduced.
• Explain what factors you considered and how they influence your final answer.
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv If I am picturing this right, you would measure less times with the single reducing the chance of error.
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Question: Later in the course you will observe how the depth of water in a uniform cylinder changes as a function of time, when water flows from a hole near the bottom of the cylinder. Suppose these measurements are made by taping a triply-reduced ruler to the side of a transparent cylinder, and observing the depth of the water at regular 3-second intervals.
The resulting data would consist of a table of water depth vs. clock times, with clock times 0, 3, 6, 9, 12, ... seconds. As depth decreases the water flows from the hole more and more slowly, so the depth changes less and less quickly with respect to clock time.
Experimental uncertainties would occur due to the optical distortion of the copied rulers, due to the spacing between marks on the rulers, due to limitations on your ability to read the ruler (your eyes are only so good), due to timing errors, and due to other possible factors.
Suppose that depth changes vary from 5 cm to 2 cm over the first six 3-second intervals.
Assume also that the timing was very precise, so that there were no significant uncertainties due to timing.
• Based on what you have learned in experiments done through Assignment 1, without doing extensive mathematical analysis, estimate how much uncertainty would be expected in the observed depths, and briefly explain the basis for your estimates. Speculate also on how much uncertainty would result in first-difference calculations done with the depth vs. clock time data, and how much in second-difference calculations.
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The error in measurement would expand up to 6 times related to the upscaling of the 3 times reduced ruler.
• How would these uncertainties affect a graph of first difference vs. midpoint clock time, and how would they affect a graph of second difference vs. midpoint clock time?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The data would be 3 to 6 times as scattered.
• How reliably do you think the first-difference graph would predict the actual behavior of the first difference?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv It would indicate the error quickly.
• Answer the same for the second-difference graph.
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv You would have to have a big graph to contain the points.
• What do you think the first difference tells you about the system? What about the second difference?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv The first would tell you the average change in rate and the second would be fairly unreliable.
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Question: Suppose the actual second-difference behavior of the depth vs. clock time is in fact linear. How nearly do you think you could estimate the slope of that graph from data taken as indicated above (e.g., within 1% of the correct slope, within 10%, within 30%, or would no slope be apparent in the second-difference graph)?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv About 10%,
Again no extensive analysis is expected, but give a brief synopsis of how you considered various effects in arriving at your estimate.
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv Most of my analysis came from visualizing graphs with the discussed data.
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