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Phy 201
Your 'cq_1_00.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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Asst 0 Question 1
The problem:
You don't have to actually do so, but it should be clear that if you wished to do so, you could take several observations of positions and clock times. The main point here is to think about how you would use that information if you did go to the trouble of collecting it. However, most students do not answer these questions in terms of position and clock time information. Some students do not pause the video as instructed. To be sure you are thinking in terms of positions and clock times, please take a minute to do the following, which should not take you more than a couple of minutes:
• Pick one of the videos, and write down the position and clock time of one of the objects, as best you can determine them, in each of three different frames. The three frames should all depict the same 'roll' down the ramp, i.e. the same video clip, at three different clock times. They should not include information from two or more different video clips.
• For each of the three readings, simply write down the clock time as it appears on the computer screen, and the position of the object along the meter stick. You can choose either object (i.e., either the pendulum or the roll of tape), but use the same object for all three measurements. Do not go to a lot of trouble to estimate the position with great accuracy. Just make the best estimates you can in a couple of minutes.
Which object did you choose and what were the three positions and the three clock times?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
pendulum
59.359 at 5 inches
59.687 at 10.5 inches
59.796 at 14 inches
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In the following you don't have to actually do calculations with your actual data. Simply explain how you would use data of this nature if you had a series of several position vs. clock time observations:
• If you did use observations of positions and clock times from this video, how accurately do you think you could determine the positions, and how accurately do you think you would know the clock times? Give a reasonable numerical answer to this question (e.g., positions within 1 meter, within 2 centimeters, within 3 inches, etc; clock times within 3 seconds, or within .002 seconds, or within .4 seconds, etc.). You should include an explanations of the basis for your estimate: Why did you make the estimate you did?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I make this estimate because the other object, regardless of which one you are taking data on, is in the way in most shots so it is hard to see the marks on the ruler. I would say that your answer could be within 0.6 inches from the actual answer. I am somewhat confused by the clock time accuracy because I would think that number would be correct since it's automated. Is it asking the efficiency of our clicking pause or if that time is actually correct? I would say within 1 second of accuracy.
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Certainly the TIMER is accurate to within 1 second.
Are the times shown accurate to within .1 second? How about .01 second? How about .001 second?
What evidence is there related to the accuracy of the TIMER?
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• How can you use observations of position and clock time to determine whether the tape rolling along an incline is speeding up or slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line): You can take data from let's say 10 pauses. Then compare the difference of length a to length b (5 in. to 10.5 in) to the time 59.359 to 59.687 then length b to length c (10.5 in. to 14 in.) to the time 59.687 to 59.796. You must compare ratios since the length of a to b and b to c are different. So, 10.5-4=5.5 and the time difference was 0.328. That ratio equals 0.0596. The next one, 14-10.5=3.5 in and the time difference was 0.109. That ratio equals 0.0311. Since the first ratio is larger than the second then it is getting faster because less time per length rolled is used.
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• How can you use observations of position and clock time to determine whether the swinging pendulum is speeding up or slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line): The same way that you determine if the tape is speeding up or slowing down. You would just have to decide if you were taking measurements from the left or right side of the pendulum and stick to that for all measurements. You could also compare if it is in front of or behind the roll of tape as they move and determine.
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• Challenge (University Physics students should attempt answer Challenge questions; Principles of Physics and General College Physics may do so but it is optional for these students): It is obvious that a pendulum swinging back and forth speeds up at times, and slows down at times. How could you determine, by measuring positions and clock times, at what location a swinging pendulum starts slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
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• Challenge (University Physics students should attempt answer Challenge questions; Principles of Physics and General College Physics may do so but it is optional for these students): How could you use your observations to determine whether the rate at which the tape is speeding up is constant, increasing or decreasing?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
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&#Good work. See my notes and let me know if you have questions. &#